案例2：健康栏目的实现

实现思路：主要是WebView的应用。先写好布局文件，布局文件中先写好头部，再实现分栏的效果，在分栏的布局文件中添加头部文件，即可实现如下图的效果，再给各部分添加相应的事件处理，同时设计到了ViewPager的使用。

遇到的问题：在导android.view.ViewGroup.LayoutParams包时，导错了包，导致程序运行时闪退，因为LayoutParams包有几十个，容易导错，后来通过查资料解决。

一、实现效果图：







二、主要代码：

1、java代码：

（1）HealthActivity.java:

package com.example.webview;

/**
* 1414110623
* @author 张钢
*/

import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.app.Activity;
import android.support.v4.view.ViewPager;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.View;
import android.view.Window;
import android.widget.ImageView;
import android.view.ViewGroup.LayoutParams;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.view.View.OnClickListener;
import android.support.v4.view.ViewPager.OnPageChangeListener;

public class HealthActivity extends Activity {
private int currIndex;// 当前页卡编号
private TextView tvCursor;
private TextView tvHealthNews;
private TextView tvIllnessDefense;
private ViewPager vpHealth;
private ImageView ivHealthBack;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_health);
initViews();
initCursor();
initViewPager();
setListeners();
}

private void initViews() {
ivHealthBack = (ImageView) findViewById(R.id.icons_health_back);
tvCursor = (TextView) findViewById(R.id.cursor);
tvHealthNews = (TextView) findViewById(R.id.tv_healthnews);
tvIllnessDefense = (TextView) findViewById(R.id.tv_healthill);
vpHealth = (ViewPager) findViewById(R.id.viewpager);
}

private void initCursor() {
Display display = getWindow().getWindowManager().getDefaultDisplay();
DisplayMetrics metrics = new DisplayMetrics();
display.getMetrics(metrics);
// 取得手机屏幕宽度的一半
int tabLineLength = metrics.widthPixels / 2;
// 设置游标的宽度为屏幕宽度的一半
LayoutParams lp = (LayoutParams) tvCursor.getLayoutParams();
lp.width = tabLineLength;
tvCursor.setLayoutParams(lp);
}

private void initViewPager() {
vpHealth = (ViewPager) findViewById(R.id.viewpager);
List<View> views = new ArrayList<View>();
views.add(new HealthWebView(this)
.getView("http://cms.hxky.cn/wap/jkxz/"));
views.add(new HealthWebView(this)
.getView("http://cms.hxky.cn/wap/jbfz/"));
vpHealth.setAdapter(new HealthViewPagerAdapter(views));
// 给 ViewPager 设置适配器
vpHealth.setCurrentItem(0);// 设置当前显示标签页为第一页
}

private void setListeners() {
// 返回按钮
ivHealthBack.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
finish();
}
});

// 点击健康须知
tvHealthNews.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
vpHealth.setCurrentItem(0);
}
});

// 点击疾病防治
tvIllnessDefense.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
vpHealth.setCurrentItem(1);
}
});

vpHealth.setOnPageChangeListener(new OnPageChangeListener() {
@Override
public void onPageSelected(int position) {
currIndex = position;
}

@Override
public void onPageScrolled(int position, float percent, int ag2) {
LinearLayout.LayoutParams ll = (android.widget.LinearLayout.LayoutParams) tvCursor
.getLayoutParams();
if (currIndex == position) {
ll.leftMargin = (int) (currIndex * tvCursor.getWidth() + percent
* tvCursor.getWidth());
} else if (currIndex > position) {
ll.leftMargin = (int) (currIndex * tvCursor.getWidth() - (1 - percent)
* tvCursor.getWidth());
}
tvCursor.setLayoutParams(ll);
}

@Override
public void onPageScrollStateChanged(int position) {
}
});
}
}

（2）HealthWebView.java：

package com.example.webview;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class HealthWebView {
private Context context;

public HealthWebView(Context context) {
this.context = context;
}

public View getView(String url) {
View view = LayoutInflater.from(context).inflate(
R.layout.pagerofhealth, null);
WebView webView = (WebView) view.findViewById(R.id.wvHealth);
webView.loadUrl(url);
// 设置支持 JavaScript 脚本
webView.getSettings().setJavaScriptEnabled(true);
/**
* 禁止系统浏览器打开页面
*/
webView.setWebViewClient(new WebViewClient() {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;
}
});
return view;
}
}

（3）HealthViewPagerAdapter.java：

package com.example.webview;

import java.util.List;
import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;

public class HealthViewPagerAdapter extends PagerAdapter {
private List<View> viewList;

public HealthViewPagerAdapter(List<View> viewList) {

this.viewList = viewList;
}

@Override
public int getCount() {
return viewList.size();
}

@Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
container.addView(viewList.get(position));
return viewList.get(position);
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView(viewList.get(position));
}
}

2、布局文件：

（1）health_layout_titlebar.xml：

这是头部的布局文件，定义了一个ImgeView和一个TextView，分别对应返回图标和“健康”标题，注意在TextView中添加： android:layout_weight="1"，到达填充标题栏的效果。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="@drawable/titlebar_bg" >

<ImageView
android:id="@+id/icons_health_back"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center"
android:paddingLeft="6dp"
android:src="@drawable/icons_health_back" />

<TextView
android:id="@+id/title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="1"
android:gravity="center"
android:text="健康"
android:textColor="#ffffff"
android:textSize="15sp" />

</LinearLayout>

（2）activity_health.xml：
这一部分是两个TextView，对应着“健康新知”和“疾病防治”两个分栏，注意这里还添加了一个ViewPager，实现游标随着两个栏目之间的切换而移动的效果，增强了浏览性。

<?xml version="1.0" encoding="utf-8"?>
<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"
tools:context=".HealthActivity" >

<include layout="@layout/health_layout_titlebar" />

<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content" >

<!-- 健康新知 -->

<TextView
android:id="@+id/tv_healthnews"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="1"
android:gravity="center"
android:padding="6dp"
android:text="@string/healthnews"
android:textSize="18sp" />

<!-- 疾病防治 -->

<TextView
android:id="@+id/tv_healthill"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="1"
android:gravity="center"
android:padding="6dp"
android:text="@string/illdefense"
android:textSize="18sp" />
</LinearLayout>

<TextView
android:id="@+id/cursor"
android:layout_width="125dp"
android:layout_height="5dp"
android:layout_marginLeft="20dp"
android:background="#990033" />

<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent" />

</LinearLayout>

（3）pagerofhealth.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<WebView
android:id="@+id/wvHealth"
android:layout_width="match_parent"
android:layout_height="match_parent" />

</RelativeLayout>

3、注册文件：

添加一句网络访问权限即可：

<uses-permission android:name="android.permission.INTERNET" />