Android--序列化/数据存入、读出SD卡

序列化
内外存储写对象，需要写对象，在内存中传递对象，A activity 传入b activity中需要序列化。
序列化两种：serializable、Parcelable
支持可序列化：
对象读写文件推荐使用：serializable
在JAVA中建议使用Parcelable

例题：将数据传入SD卡中，启动就会读取

本题有两种方法：1.传入字符串：读取时根据分割字符读取
2.传入一个实体类
本题中使用第一种，在此给出第二种的方法

//传进去一个Object类       ok.setOnClickListener(new View.OnClickListener() {           @Override          public void onClick(View v) {              Message message=new Message();              message.setTitle(c1.isChecked());            message.setChajian(c3.isChecked());               message.setInformation(c2.isChecked());              message.setRead(c4.isChecked());               message.setCollection(c5.isChecked());               message.setCollection(c6.isChecked());                message.setSize(tv3.getText().toString());String statu=Environment.getExternalStorageState();   if (!statu.equals(Environment.MEDIA_MOUNTED)){      Toast.makeText(SettingSDActivity.this,"SD卡未就绪",Toast.LENGTH_SHORT).show();               return ;            } File root=Environment.getExternalStorageDirectory();               FileOutputStream fos=null;              ObjectOutputStream oos=null;               try {                  fos=new FileOutputStream(root+"/settings.txt");                   try {                     oos=new ObjectOutputStream(fos);                      oos.writeObject(message);                  } catch (IOException e) {                      e.printStackTrace();                   }               } catch (FileNotFoundException e) {                   e.printStackTrace();             }finally {                  if (fos != null) {                      try {                          fos.close();                      fos.flush();                     } catch (IOException e) {                           e.printStackTrace();                      }                    }                }           }      });     }

下面是实体对象的class文件
此处继承了Serializable 接口，实现序列化

public class Message implements Serializable {    private Boolean title;    private String size;    private Boolean information;    private Boolean chajian;    private Boolean read;    private Boolean collection;    private Boolean top;    public Message(Boolean title, String size, Boolean information, Boolean chajian, Boolean read, Boolean collection, Boolean top) {        this.title = title;        this.size = size;        this.information = information;        this.chajian = chajian;        this.read = read;        this.collection = collection;        this.top = top;    }    public Boolean getTitle() {        return title;    }    public void setTitle(Boolean title) {        this.title = title;    }    public String getSize() {        return size;    }    public void setSize(String size) {        this.size = size;    }    public Boolean getInformation() {        return information;    }    public void setInformation(Boolean information) {        this.information = information;    }    public Boolean getChajian() {        return chajian;    }    public void setChajian(Boolean chajian) {        this.chajian = chajian;    }    public Boolean getRead() {        return read;    }    public void setRead(Boolean read) {        this.read = read;    }    public Boolean getCollection() {        return collection;    }    public void setCollection(Boolean collection) {        this.collection = collection;    }    public Boolean getTop() {        return top;    }    public void setTop(Boolean top) {        this.top = top;    }    public Message() {    }}

下面为第一种方法代码：需要注意的是开始没有文件，会报错，需要加如判断。

public class SettingSDActivity extends AppCompatActivity {    private CheckBox c1,c2,c3,c4,c5,c6;    private TextView tv3,ok;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_setting_sd);        c1=(CheckBox)findViewById(R.id.c1);        c2=(CheckBox)findViewById(R.id.c2);        c3=(CheckBox)findViewById(R.id.c3);        c4=(CheckBox)findViewById(R.id.c4);        c5=(CheckBox)findViewById(R.id.c5);        c6=(CheckBox)findViewById(R.id.c6);        tv3=(TextView)findViewById(R.id.tv3);        ok=(TextView)findViewById(R.id.ok);        tv3.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                AlertDialog.Builder builder=new AlertDialog.Builder(SettingSDActivity.this);                builder.setTitle("字体大小请选择");                builder.setIcon(R.mipmap.ic_launcher);                final String[] items={"大","中","小"};                // builder.setMultiChoiceItems()多选                builder.setSingleChoiceItems(items, 1, new DialogInterface.OnClickListener() {                    @Override                    public void onClick(DialogInterface dialog, int i) {                        Toast.makeText(getBaseContext(), items[i].toString(), Toast.LENGTH_SHORT).show();                        tv3.setText(items[i].toString());                        dialog.dismiss();                    }                });                builder.setCancelable(false);                AlertDialog alertDialog=builder.create();                alertDialog.show();            }        });        ok.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                saveFile();            }        });//保存到SD卡上，    public  void saveFile(){        FileOutputStream fos=null;        //获取SD卡状态        String state= Environment.getExternalStorageState();        //判断SD卡是否就绪        if(!state.equals(Environment.MEDIA_MOUNTED)){            Toast.makeText(this, "请检查SD卡", Toast.LENGTH_SHORT).show();            return;        }        //取得SD卡根目录        File file= Environment.getExternalStorageDirectory();        try {            Log.d("=====SD卡根目录：", file.getCanonicalPath().toString());            //输出流的构造参数1：可以是File对象，也可以是文件路径            //输出流的构造参数2：默认为fasle=>覆盖内容：true=>追加内容//            File myFile=new File(file.getCanonicalPath()+"/sd.txt");//            fos=new FileOutputStream(myFile);            //加true追加模式            //文件位置            fos=new FileOutputStream(file.getCanonicalPath()+"/sd.txt");            String  str=content();            fos.write(str.getBytes());            Toast.makeText(this,"保存成功",Toast.LENGTH_SHORT).show();        } catch (IOException e) {            e.printStackTrace();        }finally {            if (fos!=null){                try {                    fos.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }    }    public String content(){        String a,b,c,d,e,f,g,h;        if(c1.isChecked()){            a="check";        }else{            a="uncheck";        }        if(c2.isChecked()){            b="check";        }else{            b="uncheck";        }        if(c3.isChecked()){            c="check";        }else{            c="uncheck";        }        if(c4.isChecked()){            d="check";        }else{            d="uncheck";        }        if(c5.isChecked()){            e="check";        }else{            e="uncheck";        }        if(c6.isChecked()){           f="check";        }else{            f="uncheck";        }        g=tv3.getText().toString();        h=a+"#"+g+"#"+b+"#"+c+"#"+d+"#"+e+"#"+f;        return h;    }//读取文件    public String  readFile(){        BufferedReader reader=null;        FileInputStream fis=null;        StringBuilder sbd=new StringBuilder();        String statu=Environment.getExternalStorageState();        if (!statu.equals(Environment.MEDIA_MOUNTED)){            Toast.makeText(this,"SD卡未就绪",Toast.LENGTH_SHORT).show();            return  "";        }        //拿到SD卡根目录        File root=Environment.getExternalStorageDirectory();        try {            fis=new FileInputStream(root+"/sd.txt");            reader= new BufferedReader(new InputStreamReader(fis));            String row="";            try {                while ((row=reader.readLine())!=null){                    sbd.append(row);                }            } catch (IOException e) {                e.printStackTrace();            }        } catch (FileNotFoundException e) {            Toast.makeText(this,"文件不存在",Toast.LENGTH_SHORT).show();            e.printStackTrace();        }finally {            if (reader!=null){                try {                    reader.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }        return  sbd.toString();    }//一开始就读取    @Override    protected void onStart() {        super.onStart();        String my = readFile();        if(my != ""){            String k[] = my.split("#");            if (k[0].equals("check")) {                c1.setChecked(true);            } else {                c1.setChecked(false);            }            tv3.setText(k[1]);            if (k[2].equals("check")) {                c2.setChecked(true);            } else {                c2.setChecked(false);            }            if (k[3].equals("check")) {                c3.setChecked(true);            } else {                c3.setChecked(false);            }            if (k[4].equals("check")) {                c4.setChecked(true);            } else {                c4.setChecked(false);            }            if (k[5].equals("check")) {                c5.setChecked(true);            } else {                c5.setChecked(false);            }            if (k[6].equals("check")) {                c6.setChecked(true);            } else {                c6.setChecked(false);            }        }       }}

接下来是布局文件

<?xml version="1.0" encoding="utf-8"?><LinearLayout    xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent">    <LinearLayout        android:orientation="vertical"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_gravity="center_horizontal">    </LinearLayout>    <ScrollView        android:layout_width="match_parent"        android:layout_height="match_parent">        <LinearLayout            android:layout_width="match_parent"            android:layout_height="match_parent"            android:orientation="vertical"            >            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                >                <TextView                    android:layout_width="280dp"                    android:layout_height="wrap_content"                    android:text="设置"                    android:textSize="25sp"                    android:gravity="center"                    />                <TextView                    android:id="@+id/ok"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="提交"                    android:textSize="25sp"                    />            </LinearLayout>            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                >                <TextView                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="列表显示摘要"                    android:textSize="25sp"                    />                <CheckBox                    android:id="@+id/c1"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:textSize="25sp"                    android:layout_marginLeft="150dp"                    />            </LinearLayout>            <View                android:layout_width="match_parent"                android:layout_height="1dp"                android:background="#a9a8a8"                ></View>            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                android:id="@+id/LL1"                >                <TextView                    android:id="@+id/tv2"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="字体大小"                    android:textSize="25sp"                    />                <TextView                    android:id="@+id/tv3"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="中 >"                    android:textSize="25sp"                    android:layout_marginLeft="205dp"                    />            </LinearLayout>            <View                android:layout_width="match_parent"                android:layout_height="1dp"                android:background="#a9a8a8"                ></View>            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                >                <TextView                    android:id="@+id/tv4"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="列表页评论"                    android:textSize="25sp"                    />                <TextView                    android:id="@+id/tv5"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="不限 >"                    android:textSize="25sp"                    android:layout_marginLeft="153dp"                    />            </LinearLayout>            <View                android:layout_width="match_parent"                android:layout_height="1dp"                android:background="#a9a8a8"                ></View>            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                >                <TextView                    android:id="@+id/tv6"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="2G/3G网络流量"                    android:textSize="25sp"                    />                <TextView                    android:id="@+id/tv7"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="较省流量（普通下载）>"                    android:textSize="15sp"                    android:layout_marginLeft="15dp"                    />            </LinearLayout>            <View                android:layout_width="match_parent"                android:layout_height="1dp"                android:background="#a9a8a8"                ></View>            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                >                <TextView                    android:id="@+id/tv8"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="清理缓存"                    android:textSize="25sp"                    />                <TextView                    android:id="@+id/tv9"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="当前缓存：2.48MB>"                    android:textSize="20sp"                    android:layout_marginLeft="70dp"                    />            </LinearLayout>            <View                android:layout_width="match_parent"                android:layout_height="1dp"                android:background="#a9a8a8"                ></View>            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                >                <TextView                    android:id="@+id/tv10"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="推送通知"                    android:textSize="25sp"                    />                <CheckBox                    android:id="@+id/c2"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:layout_marginLeft="200dp"                    />            </LinearLayout>            <View                android:layout_width="match_parent"                android:layout_height="1dp"                android:background="#a9a8a8"                ></View>            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                >                <TextView                    android:id="@+id/tv11"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="互动插件"                    android:textSize="25sp"                    />                <CheckBox                    android:id="@+id/c3"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:layout_marginLeft="200dp"                    />            </LinearLayout>            <View                android:layout_width="match_parent"                android:layout_height="1dp"                android:background="#a9a8a8"                ></View>            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                >                <TextView                    android:id="@+id/tv12"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="自动优化阅读"                    android:textSize="25sp"                    />                <CheckBox                    android:id="@+id/c4"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:layout_marginLeft="152dp"                    />            </LinearLayout>            <View                android:layout_width="match_parent"                android:layout_height="1dp"                android:background="#a9a8a8"                ></View>            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                >                <TextView                    android:id="@+id/tv13"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="收藏时转发"                    android:textSize="25sp"                    />                <CheckBox                    android:id="@+id/c5"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:layout_marginLeft="175dp"                    />            </LinearLayout>            <View                android:layout_width="match_parent"                android:layout_height="1dp"                android:background="#a9a8a8"                ></View>            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal"                android:layout_marginTop="10dp"                android:layout_marginBottom="10dp"                >                <TextView                    android:id="@+id/tv14"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:text="顶踩时转发"                    android:textSize="25sp"                    />                <CheckBox                    android:id="@+id/c6"                    android:layout_width="wrap_content"                    android:layout_height="wrap_content"                    android:layout_marginLeft="175dp"                    />            </LinearLayout>            <View                android:layout_width="match_parent"                android:layout_height="1dp"                android:background="#a9a8a8"                ></View>        </LinearLayout>    </ScrollView></LinearLayout>

实现效果如下：