基于Android的计步器(Pedometer)的讲解(一)——Fragment页面跳转

首先需要做的是实现几个页面的跳转，既类似微信的点击按钮，切换页面。

话不多说，这是一个简单的页面切换的Demo，先贴几张实现的效果：







图片的底部是5个RadioButton，用来进行页面之间的切换。剩下的部分是一个LinearLayout的布局，用来镶嵌5个Fragment（碎片）的页面。

一共用到5个类：MainActivity、MyAdapter、FragmentHistory、FragmentAnalysis、FragmentPedometer、FragmentPK、FragmentSet

MainActivity的主要代码如下：

package com.example.changepage1;

import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.widget.RadioGroup;

public class MainActivity extends FragmentActivity {
	private RadioGroup rg;
	private List fragments;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.page_mian);
		rg = (RadioGroup) findViewById(R.id.radioGroup);//实例化radiogroup
		fragments = new ArrayList();

		//分别添加5个fragment
		fragments.add(new FragmentHistory());
		fragments.add(new FragmentAnalysis());
		fragments.add(new FragmentPedometer());
		fragments.add(new FragmentPK());
		fragments.add(new FragmentSet());
		new MyAdapter(this, fragments, R.id.Fragment, rg);//设置适配器

	}

}

MyAdapter的代码如下：

package com.example.changepage1;

import java.util.List;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;

/**
 * 这是自己写的一个适配器
 * 
 * @author 李垭超 Date: 2015-1-2 Time: 下午3点
 */
public class MyAdapter implements OnCheckedChangeListener {
	private List fragments; // 一个tab页面对应一个Fragment
	private RadioGroup rgs; // 用于切换tab
	private FragmentActivity fragmentActivity; // Fragment所属的Activity
	private int fragmentContentId; // Activity中所要被替换的区域的id

	private int currentTab = 2; // 当前Tab页面索引

	public MyAdapter(FragmentActivity fragmentActivity,
			List fragments, int fragmentContentId, RadioGroup rgs) {
		this.fragments = fragments;
		this.rgs = rgs;
		this.fragmentActivity = fragmentActivity;
		this.fragmentContentId = fragmentContentId;

		// 默认显示第一页
		FragmentTransaction ft = fragmentActivity.getSupportFragmentManager()
				.beginTransaction();
		ft.add(fragmentContentId, fragments.get(2));
		ft.commit();
		this.rgs.setOnCheckedChangeListener(this);

	}

	/**
	 * 监听radiobutton改变时间，当选择了不同的radiobutton会出发这个函数
	 */
	public void onCheckedChanged(RadioGroup group, int checkedId) {
		for (int i = 0; i < rgs.getChildCount(); i++) {
			if (rgs.getChildAt(i).getId() == checkedId) {
				Fragment fragment = fragments.get(i);
				FragmentTransaction ft = obtainFragmentTransaction(i);

				getCurrentFragment().onPause(); // 暂停当前tab

				if (fragment.isAdded()) {
					fragment.onResume(); // 启动目标tab的onResume()
				} else {
					ft.add(fragmentContentId, fragment);
				}
				showTab(i); // 显示目标tab
				ft.commit();
				

			}
		}
	}

	public Fragment getCurrentFragment() {
		return fragments.get(currentTab);
	}

	private void showTab(int idx) {
		for (int i = 0; i < fragments.size(); i++) {
			Fragment fragment = fragments.get(i);
			FragmentTransaction ft = obtainFragmentTransaction(idx);

			if (idx == i) {
				ft.show(fragment);
			} else {
				ft.hide(fragment);
			}
			ft.commit();
		}
		currentTab = idx; // 更新目标tab为当前tab

	}

	private FragmentTransaction obtainFragmentTransaction(int index) {
		FragmentTransaction ft = fragmentActivity.getSupportFragmentManager()
				.beginTransaction();
		// 设置切换动画
		if (index > currentTab) {

			ft.setCustomAnimations(R.anim.slide_left_in, R.anim.slide_left_out);
		} else {
			ft.setCustomAnimations(R.anim.slide_right_in,
					R.anim.slide_right_out);
		}
		return ft;
	}

}

FragmentHistory、FragmentAnalysis、FragmentPedometer、FragmentPK、FragmentSet的代码依次为：

package com.example.changepage1;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * 这是分析七天步数的碎片
 * Author: 李垭超   email:296777513@qq.com
 * Date: 2015-1-2
 * Time: 下午2:39
 */
public class FragmentAnalysis extends Fragment{
	private View view;

	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		view = inflater.inflate(R.layout.analysis, container, false);
		return view;
	}

}

package com.example.changepage1;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * 这是历史记录的碎片
 * Author: 李垭超   email:296777513@qq.com
 * Date: 2015-1-2
 * Time: 下午2:39
 */
public class FragmentHistory extends Fragment{
	private View view;

	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		view = inflater.inflate(R.layout.history, container, false);
		return view;
	}

}

package com.example.changepage1;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * 这是记步的碎片
 * Author: 李垭超   email:296777513@qq.com
 * Date: 2015-1-2
 * Time: 下午2:39
 */
public class FragmentPedometer extends Fragment{
	private View view;

	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		view = inflater.inflate(R.layout.pedometer, container, false);
		return view;
	}

}

package com.example.changepage1;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * 这是记步的碎片
 * Author: 李垭超   email:296777513@qq.com
 * Date: 2015-1-2
 * Time: 下午2:39
 */
public class FragmentPK extends Fragment{
	private View view;

	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		view = inflater.inflate(R.layout.pk, container, false);
		return view;
	}

}

package com.example.changepage1;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * 这是设置的碎片
 * Author: 李垭超   email:296777513@qq.com
 * Date: 2015-1-2
 * Time: 下午2:39
 */
public class FragmentSet extends Fragment{
	private View view;

	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		view = inflater.inflate(R.layout.set, container, false);
		return view;
	}

}