Android中的Parcel机制(下) 分类： Android 2014-02-08 16:57 1987人阅读 评论(3) 收藏

 上一篇中我们透过源码看到了Parcel背后的机制，本质上把它当成一个Serialize就可以了，只是它是在内存中完成的序列化和反序列化，利用的是连续的内存空间，因此会更加高效。

         我们接下来要说的是Parcel类如何应用。就应用程序而言，最常见使用Parcel类的场景就是在Activity间传递数据。没错，在Activity间使用Intent传递数据的时候，可以通过Parcelable机制传递复杂的对象。

下面来看一下简单的代码：

UserInfo类，实现了Parcelable接口:

package com.demo.entity;

import java.util.ArrayList;
import java.util.HashMap;

import android.os.Parcel;
import android.os.Parcelable;

/**
 * 用户信息，实现Parcelable接口
 * String,int,String[],ArrayList<HashMap<String,Object>>这四种类型测试
 * @author weijiang204321
 *
 */
public class UserInfo implements Parcelable{

	private String id;
	private String name;
	private int age;
	private String[] boyfriendAry = new String[3];
	private ArrayList<HashMap<String,SonInfo>> listData = new ArrayList<HashMap<String,SonInfo>>();
	private SonInfo sonInfo;
	
	public UserInfo(){
	}
	
	public UserInfo(String id,String name,int age,String[] boyfriendAry,ArrayList<HashMap<String,SonInfo>> listData){
		this.id = id;
		this.name = name;
		this.age = age;
		this.boyfriendAry = boyfriendAry;
		this.listData = listData;
	}
	
	public UserInfo(Parcel source){
		id = source.readString();
		name = source.readString();
		age = source.readInt();
		sonInfo = source.readParcelable(SonInfo.class.getClassLoader());
		source.readStringArray(boyfriendAry);
		source.readList(listData, SonInfo.class.getClassLoader());
	}
	
	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 int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}
	
	public SonInfo getSonInfo(){
		return sonInfo;
	}
	
	public void setSonInfo(SonInfo sonInfo){
		this.sonInfo = sonInfo;
	}
	
	public String[] getBoyfriendAry() {
		return boyfriendAry;
	}

	public void setBoyfriendAry(String[] boyfriendAry) {
		this.boyfriendAry = boyfriendAry;
	}

	public ArrayList<HashMap<String, SonInfo>> getListData() {
		return listData;
	}

	public void setListData(ArrayList<HashMap<String, SonInfo>> listData) {
		this.listData = listData;
	}

	
	@Override
	public int describeContents() {
		return 0;
	}

	//进行序列化存储
	@Override
	public void writeToParcel(Parcel dest, int flags) {
		dest.writeString(id);
		dest.writeString(name);
		dest.writeInt(age);
		dest.writeParcelable(sonInfo, Parcelable.PARCELABLE_WRITE_RETURN_VALUE);
		
		dest.writeStringArray(boyfriendAry);
		dest.writeList(listData);
	}
	
	public static final Parcelable.Creator<UserInfo> CREATOR = new Creator<UserInfo>() {   
        @Override  
        public UserInfo[] newArray(int size) {   
            return new UserInfo[size];   
        }   
           
        //将Parcel对象反序列化为UserInfo   
        @Override  
        public UserInfo createFromParcel(Parcel source) {   
            return new UserInfo(source);   
        }   
    };   

}

同样SonInfo类也要实现Parcelable接口:

package com.demo.entity;

import android.os.Parcel;
import android.os.Parcelable;

public class SonInfo implements Parcelable{

	private String id;
	private String name;
	
	public SonInfo(){
		
	}
	
	public SonInfo(String id,String name){
		this.id = id;
		this.name = name;
	}
	
	public SonInfo(Parcel source){
		this.id = source.readString();
		this.name = source.readString();
	}
	
	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;
	}
	
	@Override
	public int describeContents() {
		return 0;
	}
	
	@Override
	public void writeToParcel(Parcel dest, int flags) {
		dest.writeString(id);
		dest.writeString(name);
	}
	
	public static final Parcelable.Creator<SonInfo> CREATOR = new Creator<SonInfo>() {   
        @Override  
        public SonInfo[] newArray(int size) {   
            return new SonInfo[size];   
        }   
           
        //将Parcel对象反序列化为UserInfo   
        @Override  
        public SonInfo createFromParcel(Parcel source) {   
            return new SonInfo(source);   
        }   
    };   
	
}

下面来看一下测试类：

MainActivity类，在这里面进行数据的封装，然后传递到StubActivity类中：

package com.demo.parcel;

import java.util.ArrayList;
import java.util.HashMap;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;

import com.demo.entity.SonInfo;
import com.demo.entity.UserInfo;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		Intent intent = new Intent(this,StubActivity.class);
		ArrayList<HashMap<String,SonInfo>> listData = new ArrayList<HashMap<String,SonInfo>>();
		HashMap<String,SonInfo> tempMap = new HashMap<String,SonInfo>();
		tempMap.put("one_child", new SonInfo("001_1","jiangwei_one_child"));
		listData.add(tempMap);
		
		UserInfo userInfo = new UserInfo("001","jiangwei",24,new String[]{"张三","李四","王五"},listData);
		SonInfo sonInfo = new SonInfo();
		sonInfo.setId("001_1");
		sonInfo.setName("jiangwei_child");
		userInfo.setSonInfo(sonInfo);
		intent.putExtra("userinfo", userInfo);
		startActivity(intent);
		
	}

}

下面就是StubActivity类，在这个类中将读出数据进行显示:

package com.demo.parcel;

import java.util.ArrayList;
import java.util.HashMap;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

import com.demo.entity.SonInfo;
import com.demo.entity.UserInfo;

public class StubActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_stub);
		
		UserInfo userInfo = (UserInfo)this.getIntent().getParcelableExtra("userinfo");
		SonInfo sonInfo = userInfo.getSonInfo();
		
		String[] boyfriend = userInfo.getBoyfriendAry();
		for(int i=0;i<boyfriend.length;i++){
			Log.e("boyfriend_name:",boyfriend[i]);
		}
		
		ArrayList<HashMap<String,SonInfo>> listData = userInfo.getListData();
		for(int j=0;j<listData.size();j++){
			SonInfo temp_soninfo = listData.get(j).get("one_child");
			Log.e("OneChildId:",temp_soninfo.getId()+"");
			Log.e("OneChildName:",temp_soninfo.getName()+"");
		}
		
		
		
		Log.e("UserId:",userInfo.getId()+"");
		Log.e("UserName:",userInfo.getName()+"");
		Log.e("UserAge:",userInfo.getAge()+"");
		Log.e("Son_id:",sonInfo.getId()+"");
		Log.e("Son_name:",sonInfo.getName()+"");
		
	}

}

运行结果：

这样就成功了使用了Parcelable进行数据的传输

       

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