android Fragment实现Tab功能（fragment相互切换时，可保存之前状态）

转载请标明出处：http://blog.csdn.net/jjsyjiao/article/details/40980909

由于TabHost已经逐渐过时，现在开发已经不建议使用，将由Fragment代替，本文主要讲述Fragment替换TabHost的方法，代码简单易懂，适合初学者使用。

上个效果图先：

首先：

1、建个资源文件activity_main.xml;

    其中FrameLayout就是承载着Fragment的容器；

2、接下来编写我们的Activity，注意：Activity需要继承FragmentActivity，不然调用getSupportFragmentManager()方法会提示“The method getSupportFragmentManager() is undefined for the type MainActivity”；

package com.example.tab;


import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;
import android.widget.RelativeLayout;


public class MainActivity extends FragmentActivity implements OnClickListener {


	public static Context context;


	private RelativeLayout fotune, message, account, more;


	private ImageView fotune_img, message_img, account_img, more_img;


	private Fragment1 fragment1 = new Fragment1();


	private Fragment2 fragment2 = new Fragment2();


	private Fragment3 fragment3 = new Fragment3();


	private Fragment4 fragment4 = new Fragment4();


	private Bundle bundle = new Bundle();


	/**
	 * 记录当前Activity显示的fragment
	 */
	private Fragment mContent;


	private String[] textStrings = new String[] { "第一个页面——Fragment1", "第一个页面——Fragment2",
			"第一个页面——Fragment3", "第一个页面——Fragment4" };


	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		context = MainActivity.this;
		initLayout();
		if (savedInstanceState == null) {


			bundle.putString("text", textStrings[0]);
			fragment1.setArguments(bundle);
			mContent = fragment1;
			getSupportFragmentManager().beginTransaction()
					.add(R.id.container, fragment1).commit();
		}
	}


	/**
	 * 初始化控件
	 */
	private void initLayout() {
		fotune = (RelativeLayout) findViewById(R.id.fotune);
		fotune.setOnClickListener(this);
		message = (RelativeLayout) findViewById(R.id.message);
		message.setOnClickListener(this);
		account = (RelativeLayout) findViewById(R.id.account);
		account.setOnClickListener(this);
		more = (RelativeLayout) findViewById(R.id.more);
		more.setOnClickListener(this);
		fotune_img = (ImageView) findViewById(R.id.fotune_img);
		message_img = (ImageView) findViewById(R.id.message_img);
		account_img = (ImageView) findViewById(R.id.account_img);
		more_img = (ImageView) findViewById(R.id.more_img);
	}


	@Override
	public void onClick(View arg0) {
		// TODO Auto-generated method stub


		switch (arg0.getId()) {
		case R.id.fotune:


			fotune.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_onclick_color));
			message.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));
			account.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));
			more.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));


			fotune_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.fotune_a));
			message_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.message_ia));
			account_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.account_ia));
			more_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.more_ia));


			// switchContent(fragment1,
			// 0);若不想保留之前fragment的状态，每次都重新创建fragment，则选择该条命令；
			switchContent_keep(mContent, fragment1, 0);// 若想保留之前fragment的状态，则选择该条命令；
			break;
		case R.id.message:


			fotune.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));
			message.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_onclick_color));
			account.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));
			more.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));


			fotune_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.fotune_ia));
			message_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.message_a));
			account_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.account_ia));
			more_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.more_ia));


			// switchContent(fragment2,
			// 1);若不想保留之前fragment的状态，每次都重新创建fragment，则选择该条命令；
			switchContent_keep(mContent, fragment2, 1);// 若想保留之前fragment的状态，则选择该条命令；
			break;
		case R.id.account:


			fotune.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));
			message.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));
			account.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_onclick_color));
			more.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));


			fotune_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.fotune_ia));
			message_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.message_ia));
			account_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.account_a));
			more_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.more_ia));


			// switchContent(fragment3,
			// 2);若不想保留之前fragment的状态，每次都重新创建fragment，则选择该条命令；
			switchContent_keep(mContent, fragment3, 2);// 若想保留之前fragment的状态，则选择该条命令；
			break;
		case R.id.more:


			fotune.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));
			message.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));
			account.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_unclick_color));
			more.setBackgroundColor(getResources().getColor(
					R.color.bottom_background_onclick_color));


			fotune_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.fotune_ia));
			message_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.message_ia));
			account_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.account_ia));
			more_img.setBackgroundDrawable(getResources().getDrawable(
					R.drawable.more_a));


			// switchContent(fragment4,
			// 3);若不想保留之前fragment的状态，每次都重新创建fragment，则选择该条命令；
			switchContent_keep(mContent, fragment4, 3);// 若想保留之前fragment的状态，则选择该条命令；
			break;
		default:
			break;
		}
	}


	/**
	 * fragment替换（不保留之前的状态）
	 * 
	 * @param to
	 * @param i
	 */
	public void switchContent(Fragment to, int i) {
		bundle.putString("text", textStrings[i]);
		to.setArguments(bundle);
		getSupportFragmentManager().beginTransaction()
				.replace(R.id.container, to).commit();
	}


	/**
	 * fragment替换（保留之前的状态）
	 * 
	 * @param from
	 * @param to
	 * @param i
	 */
	public void switchContent_keep(Fragment from, Fragment to, int i) {
		if (from != to) {
			mContent = to;
			FragmentTransaction transaction = getSupportFragmentManager()
					.beginTransaction();
			// 先判断是否被add过
			if (!to.isAdded()) {
				bundle.putString("text", textStrings[i]);
				to.setArguments(bundle);
				// 隐藏当前的fragment，add下一个fragment到Activity中
				transaction.hide(from).add(R.id.container, to).commit();
			} else {
				// 隐藏当前的fragment，显示下一个fragment
				transaction.hide(from).show(to).commit();
				// to.onResume();该命令可注释，若希望fragment切换的过程中，被显示的fragment执行onResume方法，则解注；


			}
		}


	}
}

如果在Fragment切换的过程中，不需要保留之前Fragment的状态，直接调用getSupportFragmentManager().beginTransaction().replace(R.id.container, to).commit();即可。每次替换实质都是先remove再add，Fragment的onCreate方法都会被调用；

如果在Fragment切换的过程中，需要保留之前Fragment的状态，则需要定义一个变量Fragment mContent来保存当前activity显示fragment对象。如果你要显示的fragment对象之前未被添加过，则需要先隐藏当前显示的fragment对象，再添加你要显示的fragment对象；例如：transaction.hide(from).add(R.id.container, to).commit();若你要显示的fragment对象之前已经被添加过了，则先隐藏当前的fragment对象，再显示你要显示的fragment对象即可；例如：transaction.hide(from).show(to).commit();（注：如果此时希望调用显示的fragment对象的onResume方法，则执行to.onResume();即可。但注意的是：从fragmentActivity跳转到下一个Activity，再按返回键时，FrameLayout容器中所有的fragment都将会调用onResume方法；打印log如下所示：）

11-10 15:54:48.546: E/onCreate(19070): Fragment1
11-10 15:54:48.546: E/onCreateView(19070): Fragment1
11-10 15:54:48.546: E/onResume(19070): Fragment1
11-10 15:54:49.936: E/onCreate(19070): Fragment2
11-10 15:54:49.936: E/onCreateView(19070): Fragment2
11-10 15:54:49.936: E/onResume(19070): Fragment2
11-10 15:54:51.656: E/onCreate(19070): Fragment3
11-10 15:54:51.656: E/onCreateView(19070): Fragment3
11-10 15:54:51.656: E/onResume(19070): Fragment3
11-10 15:54:52.806: E/onCreate(19070): Fragment4
11-10 15:54:52.806: E/onCreateView(19070): Fragment4
11-10 15:54:52.806: E/onResume(19070): Fragment4
11-10 15:54:54.636: E/onResume(19070): Fragment1
11-10 15:54:54.636: E/onResume(19070): Fragment2
11-10 15:54:54.636: E/onResume(19070): Fragment3
11-10 15:54:54.636: E/onResume(19070): Fragment4

FragmentActivity向Fragment传递数据：创建个Bundle数据包，Fragment对象调用setArguments(Bundle bundle)方法即可；

Fragment接收从FragmentActivity传来的数据：调用getArguments()接收数据包，返回Bundle对象；

3、Fragment的具体实现

package com.example.tab;


import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;


public class Fragment1 extends Fragment {


	public Fragment1() {
	}


	@Override
	public void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		Log.e("onCreate", "Fragment1");
	}


	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		Log.e("onCreateView", "Fragment1");
		View rootView = inflater.inflate(R.layout.fragment_main, container,
				false);
		TextView text = (TextView) rootView.findViewById(R.id.text);
		text.setText(getArguments().getString("text"));
		Button button = (Button) rootView.findViewById(R.id.button);
		button.setOnClickListener(new OnClickListener() {


			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				Intent intent = new Intent();
				intent.setClass(MainActivity.context, SecondActivity.class);
				startActivity(intent);
			}


		});
		return rootView;
	}


	@Override
	public void onResume() {
		// TODO Auto-generated method stub
		super.onResume();
		Log.e("onResume", "Fragment1");
	}


}

Demo下载地址：http://download.csdn.net/detail/jjsyjiao/8141343