SharedPreferences 存储复杂的对象

今晚我来介绍一下SharedPreferences如何存储复杂的对象，首先我们创建一个简单对象 

package com.zb;

import java.io.Serializable;

public class Prodect implements Serializable {
	private String id;
	private String name;
	private float price;
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public float getPrice() {
		return price;
	}
	public void setPrice(float price) {
		this.price = price;
	}
}








这里的对象必须是实现Serializable接口,否则会出错

然后我们还要准备一个jar包就是commons-codec-1.4.jar,这个jar包负责将对象转换为base64的编码方式。

然我们看一下如何保存的：


package com.zb;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.StreamCorruptedException;

import org.apache.commons.codec.binary.Base64;

import android.app.Activity;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

public class SharedDemoActivity extends Activity {
	/** Called when the activity is first created. */

	private Prodect prodect;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		readProduct();
		referView();
	}

	private void init() {
		prodect = new Prodect();
		prodect.setId("1001");
		prodect.setName("红河");
		prodect.setPrice(6);
	}
	
	public void referView(){
		TextView tv=(TextView) findViewById(R.id.share);
		tv.setText(prodect==null?"错":prodect.getName());
	}

	public void readProduct() {
		SharedPreferences preferences = getSharedPreferences("base64",
				MODE_PRIVATE);
		String productBase64 = preferences.getString("product", "");
		if (productBase64 == "") {
			init();
			return;
		}
		
		//读取字节
		byte[] base64 = Base64.decodeBase64(productBase64.getBytes());
		
		//封装到字节流
		ByteArrayInputStream bais = new ByteArrayInputStream(base64);
		try {
			//再次封装
			ObjectInputStream bis = new ObjectInputStream(bais);
			try {
				//读取对象
				prodect = (Prodect) bis.readObject();
			} catch (ClassNotFoundException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		} catch (StreamCorruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public void saveProduct() {
		SharedPreferences preferences = getSharedPreferences("base64",
				MODE_PRIVATE);
		
		//创建字节输出流
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		try {
			//创建对象输出流，并封装字节流
			ObjectOutputStream oos = new ObjectOutputStream(baos);
			
			//将对象写入字节流
			oos.writeObject(prodect);

			//将字节流编码成base64的字符窜
			String productBase64 = new String(Base64.encodeBase64(baos
					.toByteArray()));

			Editor editor = preferences.edit();
			editor.putString("product", productBase64);

			editor.commit();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		Log.i("ok", "存储成功");
	}

	@Override
	protected void onStop() {
		saveProduct();
		super.onStop();

	}

}

这样就可以存储复杂的对象了！