安卓学习笔记之制作ViewPager欢迎界面

实现步骤

1. 编写布局文件
2. 编写ViewPAger适配器类
3. 初始化ViewPage，设置适配器和滑动监听
4. 初始化ViewPager数据源与页面矩形指示
5. 对ViewPager的页面滑动事件做处理，达到矩形指示跟随手的滑动而滑动
6. 实现跳转到主页

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具体代码

布局文件

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

<!-- 页面指示器 -->
<RelativeLayout
 android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true">

<LinearLayout
 android:id="@+id/ll_rect"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:paddingBottom="10dp"/>
<ImageView
 android:id="@+id/iv_greenRect"
android:layout_width="wrap_content"
android:layo android:src="@drawable/rect_green"/>

</RelativeLayout>

</RelativeLayout>

编写ViewPAger适配器类ViewPagewAdapter类

package com.yu.viewpager02;

import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;

import java.util.List;

/**
 * Created by pecu on 2016/07/06.
 */
public class ViewPagewAdapter<T> extends PagerAdapter {
    List<T> datas;

    public ViewPagewAdapter(List<T> datas) {
this.datas = datas;
    }

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

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

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


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


}

GuideActivity 类

1. 初始化ViewPage，设置适配器和滑动监听
2. 初始化ViewPager数据源与页面矩形指示
3. 对ViewPager的页面滑动事件做处理，达到矩形指示跟随手的滑动而滑动
4. 实现跳转到主页

package com.yu.viewpager02;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;

import java.util.ArrayList;
import java.util.List;

public class Guide extends Activity implements ViewPager.OnPageChangeListener {
    ViewPager vp;
int images[] = new int[]{R.mipmap.guide1, R.mipmap.guide2, R.mipmap.guide3};
    List<View> views;
    LinearLayout ll_rect; // 灰色矩形容器
    ImageView greenRect; // 绿色矩形
int rectMargin; // 矩形间隔
    Button btn_enter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initView();
        initrect();
        vp = (ViewPager) findViewById(R.id.vp);
        vp.setAdapter(new ViewPagewAdapter<View>(views));
        vp.addOnPageChangeListener(this);

    }

// 初始化用于显示到屏幕的视图
private void initView() {
        views = new ArrayList<View>();
for (int i = 0; i < images.length; i++) {
            ImageView iv = new ImageView(Guide.this);
            iv.setImageResource(images[i]);
            views.add(iv);
        }

        btn_enter = (Button) findViewById(R.id.btn_enter);
        btn_enter.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
                startActivity(new Intent(Guide.this,MainActivity.class));//跳转到主页
                finish();
            }
        });
    }

// 初始化矩形
private void initrect() {
        ll_rect = (LinearLayout) findViewById(R.id.ll_rect);
for (int i = 0; i < images.length; i++) {
            ImageView iv = new ImageView(Guide.this);
            iv.setImageResource(R.drawable.rect_grey);
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, -2);
if (i > 0) params.leftMargin = 10;  // 设置点的间距
            iv.setLayoutParams(params);
final int finalI = i;
            iv.setOnClickListener(new View.OnClickListener() {  // 设置监听事件
@Override
public void onClick(View v) {
                    vp.setCurrentItem(finalI);  // 跳转到指定页
                }
            });
            ll_rect.addView(iv);
        }

        greenRect = (ImageView) findViewById(R.id.iv_greenRect);
// 设置视图树的监听 当所有view初始化完毕时调用 用于测量两个矩形的中心的距离
        greenRect.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
                greenRect.getViewTreeObserver().removeOnGlobalLayoutListener(this);
// 两点间距
                rectMargin = ll_rect.getChildAt(1).getLeft() - ll_rect.getChildAt(0).getLeft();
            }
        });
    }

/**
 * 页面滑动时调用
 *
 * @param position
 * @param positionOffset 参数在[0,1)范围 ， 表示已滑动偏移比例
 * @param positionOffsetPixels 滑动偏移量
 */
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

// System.out.println("positionOffset:"+positionOffset+",positionOffsetPixels:"+positionOffsetPixels);
int leftMargin = (int) (position * rectMargin + positionOffset * rectMargin);
        RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) greenRect.getLayoutParams();
        params.leftMargin = leftMargin;
        greenRect.setLayoutParams(params);

    }

// 页面选中时调用
@Override
public void onPageSelected(int position) {
if (position == images.length - 1) btn_enter.setVisibility(View.VISIBLE);
else btn_enter.setVisibility(View.GONE);

    }

// 页面状态在变时调用
@Override
public void onPageScrollStateChanged(int state) {

    }



}

用于绘制矩形的shape

<!-- 当前页矩形 -->
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
<size android:height="5dp" android:width="20dp"/>
<solid android:color="#0f9"/>
</shape>


----------

<?xml version="1.0" encoding="utf-8"?>
<!-- 非选中 -->
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
<size android:height="4dp" android:width="20dp"/>
<solid android:color="#666"/>
</shape>

效果图