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