Android开发之五大存储方式之一数据库存储

废话不多说，直接看代码

activity_main:

<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:orientation="vertical" >    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal">        <EditText            android:id="@+id/et_search"            android:layout_width="0dp"            android:layout_weight="1"            android:layout_height="wrap_content"            android:hint="请输入搜索的姓名"/>        <Button            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:onClick="btn_search"            android:text="搜索" />    </LinearLayout>    <EditText        android:id="@+id/et_name"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:hint="请输入姓名" />    <EditText        android:id="@+id/et_sex"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:hint="请输入性别" />    <EditText        android:id="@+id/et_age"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:hint="请输入年龄" />    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >        <Button            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"            android:onClick="btn_insert"            android:text="添加" />        <Button            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"            android:onClick="btn_delete"            android:text="删除" />        <Button            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"            android:onClick="btn_select"            android:text="查询" />        <Button            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"            android:onClick="btn_update"            android:text="修改" />    </LinearLayout>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal"        android:background="#000000" >        <TextView            android:id="@+id/tv_id"            android:layout_width="0dp"            android:background="#ffffff"            android:layout_height="wrap_content"            android:layout_weight="1"            android:gravity="center"            android:text="学号"            android:layout_margin="3dp"            android:textColor="#ff0000" />        <TextView            android:id="@+id/tv_name"            android:layout_width="0dp"            android:background="#ffffff"            android:layout_height="wrap_content"            android:layout_weight="1"            android:gravity="center"            android:text="姓名"            android:layout_margin="3dp"            android:textColor="#ff0000" />        <TextView            android:layout_margin="3dp"            android:background="#ffffff"            android:id="@+id/tv_sex"            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"            android:gravity="center"            android:text="性别"            android:textColor="#ff0000" />        <TextView            android:background="#ffffff"            android:layout_margin="3dp"            android:id="@+id/tv_age"            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"            android:gravity="center"            android:text="年龄"            android:textColor="#ff0000" />    </LinearLayout>    <ListView        android:id="@+id/lv_list"        android:layout_width="match_parent"        android:layout_height="0dp"        android:layout_weight="1" /></LinearLayout>

item_layout:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:orientation="horizontal"    android:background="#000000" >    <TextView        android:id="@+id/tv_id"        android:layout_width="0dp"        android:background="#ffffff"        android:layout_height="wrap_content"        android:layout_weight="1"        android:gravity="center"        android:layout_margin="3dp"        android:textColor="#ff0000" />    <TextView        android:id="@+id/tv_name"        android:layout_width="0dp"        android:background="#ffffff"        android:layout_height="wrap_content"        android:layout_weight="1"        android:gravity="center"        android:layout_margin="3dp"        android:textColor="#ff0000" />    <TextView        android:layout_margin="3dp"        android:background="#ffffff"        android:id="@+id/tv_sex"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_weight="1"        android:gravity="center"        android:textColor="#ff0000" />    <TextView        android:background="#ffffff"        android:layout_margin="3dp"        android:id="@+id/tv_age"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_weight="1"        android:gravity="center"        android:textColor="#ff0000" /></LinearLayout>

Student:

package com.example.jhl.jhllearn;/** * Created by Administrator on 2016/11/4. */public class Student {    private int id;    private String name;    private String sex;    private int age;    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getSex() {        return sex;    }    public void setSex(String sex) {        this.sex = sex;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    @Override    public String toString() {        return "Student [id=" + id + ", name=" + name + ", sex=" + sex                + ", age=" + age + "]";    }    public Student(int id, String name, String sex, int age) {        super();        this.id = id;        this.name = name;        this.sex = sex;        this.age = age;    }    public Student() {        super();        // TODO Auto-generated constructor stub    }}

MyAdapter:

package com.example.jhl.jhllearn;/** * Created by Administrator on 2016/11/4. */import java.util.List;import android.content.Context;import android.view.InflateException;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.TextView;public class MyAdapter extends BaseAdapter {    private Context context;    private List<Student> oList;    private LayoutInflater inflater;    public MyAdapter(Context context,List<Student> oList)    {        this.context=context;        this.oList=oList;        this.inflater=LayoutInflater.from(context);    }    @Override    public int getCount() {        // TODO Auto-generated method stub        return oList.size();    }    @Override    public Object getItem(int position) {        // TODO Auto-generated method stub        return oList.get(position);    }    @Override    public long getItemId(int position) {        // TODO Auto-generated method stub        return position;    }    @Override    public View getView(int position, View v, ViewGroup parent) {        // TODO Auto-generated method stub        ViewHolder holder;        if (v==null) {            holder=new ViewHolder();            v=inflater.inflate(R.layout.item_layout, null);            holder.tv_id=(TextView)v.findViewById(R.id.tv_id);            holder.tv_name=(TextView)v.findViewById(R.id.tv_name);            holder.tv_sex=(TextView)v.findViewById(R.id.tv_sex);            holder.tv_age=(TextView)v.findViewById(R.id.tv_age);            v.setTag(holder);        }else {            holder=(ViewHolder)v.getTag();        }        holder.tv_id.setText( oList.get(position).getId()+"");        holder.tv_name.setText( oList.get(position).getName());        holder.tv_sex.setText( oList.get(position).getSex());        holder.tv_age.setText( oList.get(position).getAge()+"");        return v;    }    public class ViewHolder    {        TextView tv_id,tv_name,tv_sex,tv_age;    }}

MySqliteOpenHelper:

package com.example.jhl.jhllearn;/** * Created by Administrator on 2016/11/4. */import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;public class MySqliteOpenHelper extends SQLiteOpenHelper {    /**     *     * @param context     *            上下文对象     * @param name     *            数据库名称     * @param factory     *            游标工厂，默认为空     * @param version     */    // resulSet    public MySqliteOpenHelper(Context context, String name,                              CursorFactory factory, int version) {        super(context, name, factory, version);    }    @Override    public void onCreate(SQLiteDatabase db) {        // 当前第一次创建数据库的时候回调        db.execSQL("create table Student(id Integer primary key autoincrement, name varchar(10),sex varchar(4),age Integer)");    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {        // 当前数据库版本更新后，回调该方法    }}

MainActivity:

package com.example.jhl.jhllearn;import java.util.ArrayList;import java.util.List;import android.os.Bundle;import android.app.Activity;import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.view.View;import android.widget.EditText;import android.widget.ListView;import android.widget.Toast;public class MainActivity extends Activity {    private EditText et_name, et_sex, et_age, et_search;    private ListView lv_list;    private List<Student> oList = new ArrayList<Student>();    private MyAdapter adapter;    // 称为数据库辅助类，用于创建和更新    private MySqliteOpenHelper helper;    // 操作数据库增删改查    private SQLiteDatabase db;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        et_name = (EditText) findViewById(R.id.et_name);        et_sex = (EditText) findViewById(R.id.et_sex);        et_age = (EditText) findViewById(R.id.et_age);        et_search = (EditText) findViewById(R.id.et_search);        lv_list = (ListView) findViewById(R.id.lv_list);        helper = new MySqliteOpenHelper(this, "student_db", null, 1);        /**         * getReadableDatabase与getWritableDatabase sqlite数据库有一定的大小         * 当sqlite存取数据到达上线的时候，不能再写入数据 getReadableDatabase方法不允许读取，不允许写         * getWritableDatabase方法不允许写，可允许读         */        db = helper.getWritableDatabase();    }    // 向SQLite中插入数据    public void btn_insert(View v) {        // insert_sql();        insert();    }    /**     * 以insert（）方法传参方式添加数据     */    public void insert() {        String name = et_name.getText().toString();        String sex = et_sex.getText().toString();        String age = et_age.getText().toString();        // table 表名        // nullColumnHack 当我们需要插入数据时，没有明确指定字段名，默认插入数据为空        // values ：ContentValues 插入的字段值        ContentValues values = new ContentValues();        values.put("name", name);        values.put("sex", sex);        values.put("age", Integer.parseInt(age));        // {name="",sex="",age=""}        // 返回的是long类型，返回的是当前插入的数据的ID号        long index = db.insert("Student", null, values);        if (index >= 0) {            Show_Toase("插入成功" + index);        }    }    /**     * 以sql语句的形式添加数据     */    public void insert_sql() {        String name = et_name.getText().toString();        String sex = et_sex.getText().toString();        String age = et_age.getText().toString();        db.execSQL("insert into Student(name,sex,age) values(?,?,?)",                new Object[]{name, sex, Integer.parseInt(age)});        Show_Toase("添加成功");    }    public void btn_search(View v) {        if (oList.size() > 0) {            oList.clear();        }        String seach_str = et_search.getText().toString();        Cursor cursor = db.rawQuery("select * from Student where name like ?",                new String[]{"%" + seach_str + "%"});        while (cursor.moveToNext()) {            int id = cursor.getInt(cursor.getColumnIndex("id"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String sex = cursor.getString(cursor.getColumnIndex("sex"));            int age = cursor.getInt(cursor.getColumnIndex("age"));            Student student = new Student(id, name, sex, age);            oList.add(student);        }        dateSetChang();    }    private void dateSetChang() {        if (adapter == null) {            adapter = new MyAdapter(this, oList);            lv_list.setAdapter(adapter);        } else {            adapter.notifyDataSetChanged();        }    }    public void Show_Toase(String text) {        Toast.makeText(this, text, Toast.LENGTH_SHORT).show();    }    // 删除数据    public void btn_delete(View v) {        delete();        // delete_sql();    }    /**     * 以delete()方法实现删除数据     */    public void delete() {        String name = et_name.getText().toString();        String sex = et_sex.getText().toString();        String age = et_age.getText().toString();        // table 表名        // whereClause 带有占位符的条件        // whereArgs 条件所对应的值数据        // 当前整型返回的是删除记录的行数        int i = db.delete("Student", "name=? and sex=? and age=?",                new String[]{name, sex, age});        if (i > 0) {            Show_Toase("删除成功" + i);        }    }    /**     * 以sql语句的形式删除数据     */    public void delete_sql() {        String name = et_name.getText().toString();        String sex = et_sex.getText().toString();        String age = et_age.getText().toString();        db.execSQL("delete from Student where name=? and sex=? and age=?",                new Object[]{name, sex, Integer.parseInt(age)});        Show_Toase("删除成功");        boolean is = false;        for (int i = 0; i < oList.size() && !is; i++) {            if (oList.get(i).getName().equals(name)                    && oList.get(i).getSex().equals(sex)                    && oList.get(i).getAge() == Integer.parseInt(age)) {                oList.remove(i);                is = true;            }        }        dateSetChang();    }    // 查询数据    public void btn_select(View v) {        query();        // query_sql();    }    /*     * 使用query()方法查询数据     */    public void query() {        if (oList.size()>0){            oList.clear();        }        // table 表名        // columns 查询的列名        // selection 带有占位符的条件        // selectionArgs 条件所对应的值        // groupBy 分组        // having 分组的条件        // orderBy 排序（分为升序ASC,降序DESC）        // select * from Student order by id asc        Cursor cursor = db.query("Student", null, null, null, null, null,                "id asc");        while (cursor.moveToNext()) {            int id = cursor.getInt(cursor.getColumnIndex("id"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String sex = cursor.getString(cursor.getColumnIndex("sex"));            int age = cursor.getInt(cursor.getColumnIndex("age"));            Student student = new Student(id, name, sex, age);            oList.add(student);        }        dateSetChang();    }    /*     * 使用SQL语句的形式查询数据     */    public void query_sql() {        if (oList.size() > 0) {            oList.clear();        }        Cursor cursor = db.rawQuery("select * from Student", new String[]{});        while (cursor.moveToNext()) {            int id = cursor.getInt(cursor.getColumnIndex("id"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String sex = cursor.getString(cursor.getColumnIndex("sex"));            int age = cursor.getInt(cursor.getColumnIndex("age"));            Student student = new Student(id, name, sex, age);            oList.add(student);        }        dateSetChang();    }    // 更新数据    public void btn_update(View v) {        // update_sql();        update();    }    /**     * 以update()方法实现修改数据     */    public void update() {        String name = et_name.getText().toString();        String sex = et_sex.getText().toString();        String age = et_age.getText().toString();        // table 表名        // valuse ContentValues 修改后的数据        // whereClause 带占位符的条件        // whereArgs 条件的值        // update Student set name=?,age=? where sex=?        ContentValues values = new ContentValues();        values.put("name", name);        values.put("age", Integer.parseInt(age));        // 返回值表示执行修改语句后，别修改了的行数        int i = db.update("Student", values, "sex=?", new String[]{sex});        if (i > 0) {            Show_Toase("修改成功" + i);        }    }    /*     * 以sql语句的形式修改数据     */    public void update_sql() {        String name = et_name.getText().toString();        String sex = et_sex.getText().toString();        String age = et_age.getText().toString();        db.execSQL("update Student set name=?,age=? where sex=?", new Object[]{                name, Integer.parseInt(age), sex});        Show_Toase("修改成功");        for (int i = 0; i < oList.size(); i++) {            if (oList.get(i).getSex().equals(sex)) {                oList.get(i).setName(name);                oList.get(i).setAge(Integer.parseInt(age));            }        }        dateSetChang();    }}

到这里，数据库存储就OVER了，其实上面是有BUG的，比如插入的时候我的条件是根据name,age,sex,如果你有一种未填写的话，是会崩掉的，因为我没判断。这篇文章我只是具体介绍怎么学习操作数据库，其他的没去做太多处理，读者自行完善

最后如果想看创建的数据库的效果话首先必须是模拟器，真机是没用的，然后下载一个操作数据库的SQLite，下载地址：http://download.csdn.net/detail/qq_33750826/9673234
然后安装打开

然后打开AndroidStudio或者Eclipse的File Explorer:
在里面找到data->data->找到自己的项目包名