Android开发之app基础框架ViewPager+Fragment

一个app，从引导页面进入后，就会进入一个显示app内容的页面，现在主流的几个界面主要是viewPager+fragment或者是侧滑，作为一个Android开发者，这些是必须要掌握的，下面就说说常见的ViewPager+fragment基本ui框架。

动态添加Fragment主要分为4步：

1.获取到FragmentManager，在Activity中可以直接通过getFragmentManager得到。

2.开启一个事务，通过调用beginTransaction方法开启。

3.向容器内加入Fragment，一般使用replace方法实现，需要传入容器的id和Fragment的实例。

4.提交事务，调用commit方法提交。

当然了，对于ViewPager+fragment我们可以通过继承FragmentPagerAdapter 或者FragmentPagerStateAdapter来实现，这两个之间的区别就在于，后者默认加载三个页面，而前者加载所有页面。

看了很多人写的这方面的内容，还是觉得下面的这个写的比较好！记不清是什么时候看到他写的东西了，所以没有办法著名从哪里来的，好的东西就一起分享吧！

具体代码如下：

自定义view ChangeColorIconWithTextView

主要功能是绘制底部图案和文字的view

package com.zhy.weixin6.ui;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.os.Looper;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.view.View;

public class ChangeColorIconWithTextView extends View
{

private Bitmap mBitmap;
private Canvas mCanvas;
private Paint mPaint;
/**
* 颜色
*/
private int mColor = 0xFF45C01A;
/**
* 透明度 0.0-1.0
*/
private float mAlpha = 0f;
/**
* 图标
*/
private Bitmap mIconBitmap;
/**
* 限制绘制icon的范围
*/
private Rect mIconRect;
/**
* icon底部文本
*/
private String mText = "微信";
private int mTextSize = (int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_SP, 10, getResources().getDisplayMetrics());
private Paint mTextPaint;
private Rect mTextBound = new Rect();

public ChangeColorIconWithTextView(Context context)
{
super(context);
}

/**
* 初始化自定义属性值
*
* @param context
* @param attrs
*/
public ChangeColorIconWithTextView(Context context, AttributeSet attrs)
{
super(context, attrs);

// 获取设置的图标
TypedArray a = context.obtainStyledAttributes(attrs,
R.styleable.ChangeColorIconView);

int n = a.getIndexCount();
for (int i = 0; i < n; i++)
{

int attr = a.getIndex(i);
switch (attr)
{
case R.styleable.ChangeColorIconView_icon:
BitmapDrawable drawable = (BitmapDrawable) a.getDrawable(attr);
mIconBitmap = drawable.getBitmap();
break;
case R.styleable.ChangeColorIconView_color:
mColor = a.getColor(attr, 0x45C01A);
break;
case R.styleable.ChangeColorIconView_text:
mText = a.getString(attr);
break;
case R.styleable.ChangeColorIconView_text_size:
mTextSize = (int) a.getDimension(attr, TypedValue
.applyDimension(TypedValue.COMPLEX_UNIT_SP, 10,
getResources().getDisplayMetrics()));
break;

}
}

a.recycle();

mTextPaint = new Paint();
mTextPaint.setTextSize(mTextSize);
mTextPaint.setColor(0xff555555);
// 得到text绘制范围
mTextPaint.getTextBounds(mText, 0, mText.length(), mTextBound);

}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
super.onMeasure(widthMeasureSpec, heightMeasureSpec);

// 得到绘制icon的宽
int bitmapWidth = Math.min(getMeasuredWidth() - getPaddingLeft()
- getPaddingRight(), getMeasuredHeight() - getPaddingTop()
- getPaddingBottom() - mTextBound.height());

int left = getMeasuredWidth() / 2 - bitmapWidth / 2;
int top = (getMeasuredHeight() - mTextBound.height()) / 2 - bitmapWidth
/ 2;
// 设置icon的绘制范围
mIconRect = new Rect(left, top, left + bitmapWidth, top + bitmapWidth);

}

@Override
protected void onDraw(Canvas canvas)
{

int alpha = (int) Math.ceil((255 * mAlpha));
canvas.drawBitmap(mIconBitmap, null, mIconRect, null);
setupTargetBitmap(alpha);
drawSourceText(canvas, alpha);
drawTargetText(canvas, alpha);
canvas.drawBitmap(mBitmap, 0, 0, null);

}

private void setupTargetBitmap(int alpha)
{
mBitmap = Bitmap.createBitmap(getMeasuredWidth(), getMeasuredHeight(),
Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
mPaint = new Paint();
mPaint.setColor(mColor);
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setAlpha(alpha);
mCanvas.drawRect(mIconRect, mPaint);
mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
mPaint.setAlpha(255);
mCanvas.drawBitmap(mIconBitmap, null, mIconRect, mPaint);
}

private void drawSourceText(Canvas canvas, int alpha)
{
mTextPaint.setTextSize(mTextSize);
mTextPaint.setColor(0xff333333);
mTextPaint.setAlpha(255 - alpha);
canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2
- mTextBound.width() / 2,
mIconRect.bottom + mTextBound.height(), mTextPaint);
}

private void drawTargetText(Canvas canvas, int alpha)
{
mTextPaint.setColor(mColor);
mTextPaint.setAlpha(alpha);
canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2
- mTextBound.width() / 2,
mIconRect.bottom + mTextBound.height(), mTextPaint);

}

public void setIconAlpha(float alpha)
{
this.mAlpha = alpha;
invalidateView();
}

private void invalidateView()
{
if (Looper.getMainLooper() == Looper.myLooper())
{
invalidate();
} else
{
postInvalidate();
}
}

public void setIconColor(int color)
{
mColor = color;
}

public void setIcon(int resId)
{
this.mIconBitmap = BitmapFactory.decodeResource(getResources(), resId);
if (mIconRect != null)
invalidateView();
}

public void setIcon(Bitmap iconBitmap)
{
this.mIconBitmap = iconBitmap;
if (mIconRect != null)
invalidateView();
}

private static final String INSTANCE_STATE = "instance_state";
private static final String STATE_ALPHA = "state_alpha";

@Override
protected Parcelable onSaveInstanceState()
{
Bundle bundle = new Bundle();
bundle.putParcelable(INSTANCE_STATE, super.onSaveInstanceState());
bundle.putFloat(STATE_ALPHA, mAlpha);
return bundle;
}

@Override
protected void onRestoreInstanceState(Parcelable state)
{
if (state instanceof Bundle)
{
Bundle bundle = (Bundle) state;
mAlpha = bundle.getFloat(STATE_ALPHA);
super.onRestoreInstanceState(bundle.getParcelable(INSTANCE_STATE));
} else
{
super.onRestoreInstanceState(state);
}

}

}

其实作为单单想要用的朋友可以不用考虑这个自定义view，只需要知道他是干什么用的就行，当然，如果有兴趣还是可以分析下的！现在来说说怎么用吧，在xml中应用:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:zhy="http://schemas.android.com/apk/res/com.zhy.weixin6.ui"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<android.support.v4.view.ViewPager
android:id="@+id/id_viewpager"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1" >
</android.support.v4.view.ViewPager>

<LinearLayout
android:layout_width="fill_parent"
android:layout_height="60dp"
android:background="@drawable/tabbg"
android:orientation="horizontal" >

<com.zhy.weixin6.ui.ChangeColorIconWithTextView
android:id="@+id/id_indicator_one"
android:layout_width="0dp"
android:layout_height="fill_parent"
android:layout_weight="1"
android:padding="5dp"
zhy:icon="@drawable/ic_menu_start_conversation"
zhy:text="@string/tab_weixin"
zhy:text_size="12sp" />

<com.zhy.weixin6.ui.ChangeColorIconWithTextView
android:id="@+id/id_indicator_two"
android:layout_width="0dp"
android:layout_height="fill_parent"
android:layout_weight="1"
android:padding="5dp"
zhy:icon="@drawable/ic_menu_friendslist"
zhy:text="@string/tab_contact"
zhy:text_size="12sp" />

<com.zhy.weixin6.ui.ChangeColorIconWithTextView
android:id="@+id/id_indicator_three"
android:layout_width="0dp"
android:layout_height="fill_parent"
android:layout_weight="1"
android:padding="5dp"
zhy:icon="@drawable/ic_menu_emoticons"
zhy:text="@string/tab_find"
zhy:text_size="12sp" />

<com.zhy.weixin6.ui.ChangeColorIconWithTextView
android:id="@+id/id_indicator_four"
android:layout_width="0dp"
android:layout_height="fill_parent"
android:layout_weight="1"
android:padding="5dp"
zhy:icon="@drawable/ic_menu_allfriends"
zhy:text="@string/tab_me"
zhy:text_size="12sp" />
</LinearLayout>

</LinearLayout>

值得注意的是在布局的开头添加 xmlns:zhy=”http://schemas.android.com/apk/res/com.zhy.weixin6.ui”

http://scemas.android 后面对应的是包名 xmlns 对应的zhy 就是对应可以设置的属性，然后再xml中设置他的icon 和 text 属性就ok 了；

再来看看 MainActivcity

package com.zhy.weixin6.ui;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewConfiguration;
import android.view.Window;

@SuppressLint("NewApi")
public class MainActivity extends FragmentActivity implements
OnPageChangeListener, OnClickListener
{
private ViewPager mViewPager;
private List<Fragment> mTabs = new ArrayList<Fragment>();
private FragmentPagerAdapter mAdapter;

private String[] mTitles = new String[] { "First Fragment!",
"Second Fragment!", "Third Fragment!", "Fourth Fragment!" };

private List<ChangeColorIconWithTextView> mTabIndicator = new ArrayList<ChangeColorIconWithTextView>();

@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewPager = (ViewPager) findViewById(R.id.id_viewpager);
//初始化底部控件
initTabIndicator();
initDatas();
mViewPager.setAdapter(mAdapter);
mViewPager.setOnPageChangeListener(this);
}
//添加fragment，实际情况一个一个添加
private void initDatas()
{

for (String title : mTitles)
{
TabFragment tabFragment = new TabFragment();
Bundle args = new Bundle();
args.putString("title", title);
tabFragment.setArguments(args);
mTabs.add(tabFragment);
}

mAdapter = new FragmentPagerAdapter(getSupportFragmentManager())
{

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

@Override
public Fragment getItem(int arg0)
{
return mTabs.get(arg0);
}
};

}

private void initTabIndicator()
{
ChangeColorIconWithTextView one = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_one);
ChangeColorIconWithTextView two = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_two);
ChangeColorIconWithTextView three = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_three);
ChangeColorIconWithTextView four = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_four);

mTabIndicator.add(one);
mTabIndicator.add(two);
mTabIndicator.add(three);
mTabIndicator.add(four);

one.setOnClickListener(this);
two.setOnClickListener(this);
three.setOnClickListener(this);
four.setOnClickListener(this);

one.setIconAlpha(1.0f);
}

@Override
public void onPageSelected(int arg0)
{
}

@Override
public void onPageScrolled(int position, float positionOffset,
int positionOffsetPixels)
{
// Log.e("TAG", "position = " + position + " , positionOffset = "
// + positionOffset);

if (positionOffset > 0)
{
ChangeColorIconWithTextView left = mTabIndicator.get(position);
ChangeColorIconWithTextView right = mTabIndicator.get(position + 1);

left.setIconAlpha(1 - positionOffset);
right.setIconAlpha(positionOffset);
}

}

@Override
public void onPageScrollStateChanged(int state)
{

}

@Override
public void onClick(View v)
{

resetOtherTabs();

switch (v.getId())
{
case R.id.id_indicator_one:
//设置透明度
mTabIndicator.get(0).setIconAlpha(1.0f);
mViewPager.setCurrentItem(0, false);
break;
case R.id.id_indicator_two:
mTabIndicator.get(1).setIconAlpha(1.0f);
mViewPager.setCurrentItem(1, false);
break;
case R.id.id_indicator_three:
mTabIndicator.get(2).setIconAlpha(1.0f);
mViewPager.setCurrentItem(2, false);
break;
case R.id.id_indicator_four:
mTabIndicator.get(3).setIconAlpha(1.0f);
mViewPager.setCurrentItem(3, false);
break;

}

}

/**
* 重置其他的Tab
*/
private void resetOtherTabs()
{
for (int i = 0; i < mTabIndicator.size(); i++)
{
mTabIndicator.get(i).setIconAlpha(0);
}
}
}

再就是对应的子**Fragment**

package com.zhy.weixin6.ui;

import android.graphics.Color;

import android.os.Bundle;

import android.support.v4.app.Fragment;

import android.view.Gravity;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.TextView;

public class TabFragment extends Fragment

{

private String mTitle = “Default”;

public TabFragment()
{
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
if (getArguments() != null)
{
mTitle = getArguments().getString("title");
}

TextView textView = new TextView(getActivity());
textView.setTextSize(20);
textView.setBackgroundColor(Color.parseColor("#ffffffff"));
textView.setGravity(Gravity.CENTER);
textView.setText(mTitle);
return textView;
}

}

drawable中设置一个点击事件的tabbg.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
<stroke android:width="1dp" android:color="#eee" />
<solid android:color="#F7F7F7"/>
</shape>

再就是一个在value里面创建一个attr 文件styleavle属性：

<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="ChangeColorIconView">
<attr name="icon" />
<attr name="color" />
<attr name="text" />
<attr name="text_size" />
</declare-styleable>

</resources>

还有按钮图片就可以随便上了！代码就是这些部分了，下面来总结下viewPager+fragment的流程吧！

1.在MainActivity中实现OnPageChangeListener接口，并重写三个方法：
onPageSelected(),onPageScrolled(),onPageScrollStateChanged()
2.添加fragment，这个比较简单我就不说了
3.创建adapter，继承FragmentPagerAdapter，实现getCount(),getItem()
其实在有的需求中Fragment页面是不需要滑动的，这个时候这个框架同样可以有用，只需要实现viewPager的onTouchListener接口，代码如下

//控制viewpager不能滑動 但是能夠点击
mViewPager.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub
return true;            }
});

“`

当然了，这些代码都是我从其他地方看到的，不过都是进行了验证了的，为了自己开发中方便查看，所以记下来留做后用，希望对你有帮助！