实训10 数据存储和访问
一、【实训目的】
1、 SharedPreferences存储数据;
2、 借助Java的I/O体系实现文件的存储，
3、使用Android内置的轻量级数据库SQLite存储数据;
二、【实训内容】
1、实现下图所示的界面，实现以下功能：
1）用SharedPreferences类，当点击”写入xml文件”按钮, 把“输入你想写入内容”控件中的数据写入到login.xml文件中；
2）用SharedPreferences类，当点击”读取内容”按钮, 把content.xml文件中的数据都到一个控件中；
3）用Java的I/O体系实现文件的存储，单击“写入login.txt文件”，把数据写入到login.txt文件中；
4）使用Android内置的轻量级数据库SQLite存储数据，单击“写入数据库”，把数据写入到daba.db3文件中；
具体步骤：
MainActivity.java
package com.example.gf;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import android.os.Bundle;
import android.app.Activity;
import android.database.sqlite.SQLiteDatabase;
import android.content.Context;
import android.content.SharedPreferences;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity {
private SharedPreferences contentxieru;
private SharedPreferences.Editor contentEditor;
MyDBHelper dbhelper;
SQLiteDatabase db;
private Button write, read,loginxieru,mysqlxieru;
private EditText writeText, readText;
private String fileName = "login.txt";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
write = (Button) findViewById(R.id.write);
read = (Button) findViewById(R.id.read);
writeText = (EditText) findViewById(R.id.writeText);
readText = (EditText) findViewById(R.id.readText);
dbhelper=new MyDBHelper(this, "HR_DB.db3", 1);
write.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
//write(writeText.getText().toString());
contentxieru=getSharedPreferences("content", Context.MODE_PRIVATE);
contentEditor = contentxieru.edit();
contentEditor.putString("content", writeText.getText().toString());
contentEditor.commit();
}
});
read.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
//readText.setText(read());
String name=contentxieru.getString("content","none");
readText.setText(name);
}
});
loginxieru.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
write(writeText.getText().toString());
}
});
mysqlxieru.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
String sql="insert into";
db=dbhelper.getReadableDatabase();
db.execSQL(sql);
Toast.makeText(MainActivity.this, "成功添加一条员工信息", 3000).show();
}
});
}
public String read() {
StringBuilder sbBuilder = new StringBuilder("");
byte[] buffer = new byte[64];
int hasRead;
try {
FileInputStream fis = openFileInput(fileName);
while ((hasRead = fis.read(buffer)) != -1) {
sbBuilder.append(new String(buffer, 0, hasRead));
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return sbBuilder.toString();
}
public void write(String str) {
try {
FileOutputStream fos = openFileOutput(fileName, Context.MODE_APPEND);
PrintStream ps = new PrintStream(fos);
ps.print(str);
ps.close();
try {
fos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (FileNotFoundException ex) {
ex.printStackTrace();
}
}
@Override
public void onDestroy()
{
super.onDestroy();
if (db != null && db.isOpen())
{
db.close();
}
}
}MyDBHelper.java
package com.example.gf;
import android.content.Context;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class MyDBHelper extends SQLiteOpenHelper {
public MyDBHelper(Context context, String name, int version) {
super(context, name, null, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
System.out.println("x");
String CreateTableSql="create table Employee("
+"_id integer primary key autoincrement,"
+"no varchar,"
+"name varchar,"
+"sex varchar)";
db.execSQL(CreateTableSql);
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
}
}String.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">FileText</string>
<string name="action_settings">Settings</string>
<string name="hello_world">Hello world!</string>
<string name="hint">输入你想写入的内容</string>
<string name="readhint">显示读取的内容</string>
<string name="read">读取内容</string>
<string name="write">写入xml文件</string>
<string name="loginxiejin">写入login.txt文件</string>
<string name="mysqlxiejin">写入数据库</string>
</resources>Activity_main.xml
<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"
android:paddingLeft="20dp"
tools:context=".MainActivity" >
<EditText
android:id="@+id/writeText"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="@string/hint"
android:textSize="20sp" />
<Button
android:id="@+id/write"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/write"
android:textSize="20sp" />
<EditText
android:id="@+id/readText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:enabled="false"
android:textColor="#ff0000"
android:textSize="20sp" />
<Button
android:id="@+id/read"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/read"
android:textSize="20sp" />
<Button
android:id="@+id/loginxie"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/loginxiejin"
android:textSize="20sp" />
<Button
android:id="@+id/mysqlxie"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/mysqlxiejin"
android:textSize="20sp" />
</LinearLayout>运行结果截图:
附注：该专栏是博主上学时的实训项目，可供访客练习与参考。代码质量不是很好，但能实现，仅供参考！