实验六外部存储于ListView

1.ListView与SimpleAdapter

开始的时候由于使用的Android版本太高，在DDMS中的File Explorer中没有显示任何东西，可能是因为权限的问题吧。改用Android4.4后就行了。

MainActivity.javapackage zhku.edu.exp6_1;import android.app.Activity;import android.content.Context;import android.content.Intent;import android.os.Bundle;import android.os.Environment;import android.util.Log;import android.view.View;import android.widget.AdapterView;import android.widget.ListView;import android.widget.SimpleAdapter;import android.widget.TextView;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Scanner;public class MainActivity extends Activity {    TextView tv;    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        tv= (TextView) findViewById(R.id.textView1);        int[] ids={R.id.title,R.id.score,R.id.people,                R.id.edition,R.id.date,R.id.file_size,R.id.system, R.id.img};        String[] keys={"title","score","people","edition",                "date","file_size","system","img"};        List<Map<String,Object>> data=getDataFromFile();        SimpleAdapter adapter=new SimpleAdapter(this,data,R.layout.list_item,keys,ids);        ListView lv= (ListView) findViewById(R.id.listView1);        lv.setAdapter(adapter); //设置点击事件        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {    public void onItemClick(AdapterView<?> parent, View view,                            int position, long id) {        ListView listView = (ListView)parent;//获得listView        Map<String, Object> map = (Map<String, Object>)        listView.getItemAtPosition(position);//取数据        Intent intent = new Intent(MainActivity.this, BActivity.class);        ArrayList list = new ArrayList();//用来封装map 数据的list        Bundle bundle = new Bundle();        list.add(map);//添加map 数据到list        bundle.putParcelableArrayList("data", list);//传数据到bundle        intent.putExtras(bundle);        startActivity(intent);//启动下一个窗体            }        });    }    private List<Map<String,Object>> getDataFromFile() {        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();//        Map<String,Object>map=new HashMap<String,Object>();        String state = Environment.getExternalStorageState();//获取当前状态        if (state.equals(Environment.MEDIA_MOUNTED)) {            //判断SD卡是否已挂载            File SDPath = Environment.getExternalStorageDirectory();//获取外部存储根目录            String filePath = SDPath.getPath() + "/DCIM";            File file = new File(filePath, "exp6_1.txt");            FileInputStream fis = null;            try {                fis = new FileInputStream(file);            } catch (FileNotFoundException e) {                e.printStackTrace();                Log.i("getDataFromFile", "error");                return list;            }            Scanner in = new Scanner(fis);            while (in.hasNext()) {                Map<String, Object> map = new HashMap<String, Object>();                map.put("title", in.next());                map.put("score", in.next());                map.put("people", in.nextInt());                map.put("edition", in.next());                map.put("date", in.next());                map.put("file_size", in.next());                map.put("system", in.next());                String imgFile = in.next();                int id = getImageId(imgFile, this); //封装图片id 转换                map.put("img", id);                list.add(map);            }        }            return list;        }    public static int getImageId(String imgName,Context context){        String[] names=imgName.split("\\.");        if(names.length==0)            return R.drawable.ic_launcher;            int id=context.getResources().getIdentifier(names[0], "drawable", "zhku.edu.exp6_1");        if(id==0)            return R.drawable.ic_launcher;        else        return id;    }}

Activity_main.xml<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:orientation="vertical"    tools:context="zhku.edu.exp6_1.MainActivity">    <TextView        android:id="@+id/textView1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/sumtitle"        android:textColor="#0000FF"        android:textSize="18sp"/>    <ListView        android:id="@+id/listView1"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:divider="#AAAAAA"        android:dividerHeight="2px"/></LinearLayout>Lsit_item.xml<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="horizontal"    android:layout_width="match_parent"    android:layout_height="match_parent">    <ImageView        android:id="@+id/img"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        />    <RelativeLayout        android:layout_width="wrap_content"        android:layout_height="match_parent">        <TextView            android:layout_centerHorizontal="true"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:id="@+id/title"            android:textSize="20sp"/>        <TextView            android:layout_marginLeft="10dp"            android:layout_below="@+id/title"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:id="@+id/score" />        <TextView            android:id="@+id/people"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_below="@+id/title"            android:layout_toRightOf="@+id/score"/>        <TextView            android:layout_below="@+id/title"            android:layout_toRightOf="@+id/people"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:id="@+id/edition"/>        <TextView            android:layout_below="@+id/title"            android:layout_toRightOf="@+id/edition"            android:layout_width="wrap_content"            android:layout_height="wrap_content"           android:id="@+id/date" />        <TextView            android:layout_below="@+id/title"            android:layout_toRightOf="@+id/date"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:id="@+id/file_size" />        <TextView            android:layout_below="@+id/title"            android:layout_toRightOf="@+id/file_size"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:id="@+id/system" />    </RelativeLayout></LinearLayout>

结果显示：

2.文件外部存储

BActivity.javapackage zhku.edu.exp6_1;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.TextView;import java.util.ArrayList;import java.util.Map;public class BActivity extends Activity implements View.OnClickListener {    TextView topTitle,tv_score,tv_people,tv_title;    Button btn_sure,btn_cancel;    Map<String, Object>map;    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_b);        Intent it = getIntent();        Bundle bundle = it.getExtras();//接收传入数据        ArrayList list = bundle.getParcelableArrayList("data");        map = (Map<String, Object>) list.get(0);//map 是BActivity 的成员变量         RefreshData();//在界面上TextView 显示map 中的数据        btn_sure= (Button) findViewById(R.id.btn_sure);        btn_cancel= (Button) findViewById(R.id.btn_cancel);        btn_sure.setOnClickListener(this);        btn_cancel.setOnClickListener(this);    }    public void onClick(View v){        if(v.getId()==R.id.btn_sure){//点击确定按钮，更新数据            Double score=Double.parseDouble(map.get("score").toString());            int people=Integer.parseInt(map.get("people").toString());            score=(score*people+100)/(people+1);            people=people+1;            String aftScore=String.format("%.3f",score);//保留小数点后3位            String aftPeople=String.valueOf(people);            tv_score.setText(aftScore);            tv_people.setText(aftPeople);        }        else if(v.getId()==R.id.btn_cancel){//点击取消按钮，返回到MainActivity            finish();        }    }    private void RefreshData() {        topTitle= (TextView) findViewById(R.id.tv_Toptitle);        tv_score= (TextView) findViewById(R.id.tv_score);        tv_people= (TextView) findViewById(R.id.tv_people);        tv_title= (TextView) findViewById(R.id.tv_title);        String perScore=map.get("score").toString();        String prePeople=map.get("people").toString();        String preTitle=map.get("title").toString();        topTitle.setText(preTitle);        tv_score.setText(perScore);        tv_people.setText(prePeople);        tv_title.setText(preTitle);    }}

Activity_b.xml<?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">    <TextView        android:id="@+id/tv_Toptitle"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:textSize="35sp"        android:textColor="#0000ff"/>    <LinearLayout        android:layout_marginTop="15dp"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="horizontal">    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/score"        android:textSize="20sp"/>        <TextView            android:id="@+id/tv_score"            android:layout_width="200dp"            android:layout_height="26dp"            android:textSize="20sp"            android:textColor="#ff0000"/>    </LinearLayout>    <LinearLayout        android:layout_marginTop="20dp"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="horizontal">        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="@string/people"            android:textSize="25sp"/>        <TextView            android:id="@+id/tv_people"            android:layout_width="200dp"            android:layout_height="26dp"            android:textSize="20sp"            android:textColor="#ff0000"/>    </LinearLayout>    <LinearLayout        android:layout_marginTop="20dp"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="horizontal">        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="@string/sure1"            android:textSize="20sp"/>        <TextView            android:id="@+id/tv_title"            android:layout_width="250dp"            android:layout_height="26dp"            android:textSize="18sp"            android:textColor="#ff0000"/>    </LinearLayout>    <TextView        android:layout_marginLeft="30sp"        android:layout_marginTop="15dp"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/sure2"        android:textSize="20sp"/><LinearLayout    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:orientation="horizontal">    <Button        android:id="@+id/btn_sure"        android:layout_marginTop="50dp"        android:layout_marginLeft="30dp"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/sure"        android:background="#00ff00"/>    <Button        android:id="@+id/btn_cancel"        android:layout_marginTop="50dp"        android:layout_marginLeft="120dp"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/cancel"        android:background="#ffff00"/>    </LinearLayout></LinearLayout>

结果显示：