纯代码实现button+fragment底部菜单栏

首先说说为什么要用纯代码。

纯代码布局的适用性强，对于一些打包，混淆加密，资源管理等具备一定的优势。而且代码动态布局使用起来感觉让人更便利，一次封装就能随心所欲的控制。

但同时纯代码布局也会有很多弊端，比如界面无法用IDE及时实现可视化，调试困难，没有阅读纯代码习惯的话会造成一定的困扰，对新手来讲更是觉得有些难以阅读，如果项目架构不明确的话更是让人难以维护。

现在的纯代码布局多数用于一些SDK插件之中，打包的便利性会让SDK集成变得相当容易，抛弃了res文件的copy，开发也不用去利用Java有些跳跃的反射机制去读取资源ID，这样，集成起来可能只需要一个jar就可以了，然后配置主文件，调用接口即可。

好了，言归正传，开始说说纯代码实现的这个例子。

首先看下act的内容，相当简单。

package com.example.test;

import java.util.ArrayList;

import android.app.Activity;
import android.os.Bundle;

import com.example.test.fragment.AFragment;
import com.example.test.fragment.BFragment;
import com.example.test.fragment.CFragment;
import com.example.test.fragment.DFragment;
import com.example.test.frame.MainView;
import com.example.test.frame.MenuInfo;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ArrayList<MenuInfo> infos = new ArrayList<MenuInfo>();
infos.add(new MenuInfo(0, R.drawable.b, R.drawable.a, "首页",new AFragment()));
infos.add(new MenuInfo(1, R.drawable.b, R.drawable.a, "云播",new BFragment()));
infos.add(new MenuInfo(2, R.drawable.b, R.drawable.a, "博客",new CFragment()));
infos.add(new MenuInfo(3, R.drawable.b, R.drawable.a, "我",new DFragment()));
MainView mv = new MainView(this,infos,0);
setContentView(mv);
}
}

看上去是不是很简单？ 代码里有用到MainView跟MenuInfo这两个类，我们先上MenuInfo的代码：

package com.example.test.frame;

import android.app.Fragment;

public class MenuInfo {

public int id;
public int downImg;
public int upImg;
public String text;
public Fragment f;

public MenuInfo(int id, int downImg, int upImg, String text,Fragment f) {
super();
this.id = id;
this.downImg = downImg;
this.upImg = upImg;
this.text = text;
this.f = f;
}
}

可以看到这实际上是一个实体类，里面封装了我们需要的一些信息，id，按下去的图片，弹起的图片，标题文本，还有fragment。act中用到的就是这个了，我们把这个实体放到一个ArrayList中，然后再根据MainView去动态的创建我们需要的视图，底部需要几个按钮就创建几个实体。那我们看看这个神奇的MainView究竟怎么实现的。

package com.example.test.frame;

import java.util.ArrayList;

import android.app.Activity;
import android.app.FragmentTransaction;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainView extends LinearLayout implements OnClickListener {

private Activity mActivity;
private ArrayList<MenuInfo> infos;
private ImageView iv;
private TextView tv;
private int oldId;
private FrameLayout flayout;

private int textUp = 0xffffffff;
private int textDown = 0xff3e3e3e;

public MainView(Activity act, ArrayList<MenuInfo> infos, int id) {
super(act);
this.mActivity = act;
this.infos = infos;
this.setOrientation(LinearLayout.VERTICAL);
this.oldId = infos.get(0).id;
init();
initItem();
defClick(id);
}

private void init() {
flayout = new FrameLayout(mActivity);
flayout.setId(0x9527);
LinearLayout.LayoutParams llp = new LayoutParams(-1, -2);
llp.weight = 1;
this.addView(flayout, llp);
}

private void initItem() {
LinearLayout bottomLayout = new LinearLayout(mActivity);
bottomLayout.setOrientation(LinearLayout.HORIZONTAL);
bottomLayout.setGravity(Gravity.CENTER);
bottomLayout.setBackgroundColor(0xffeeeeee);
this.addView(bottomLayout);

LayoutParams lp = new LayoutParams(-1, -1);
lp.weight = 1;

LayoutParams llp = new LayoutParams(-2, -2);
llp.gravity = Gravity.CENTER;

for (MenuInfo mMenuInfo : infos) {

LinearLayout item = new LinearLayout(mActivity);
item.setOrientation(LinearLayout.VERTICAL);
item.setId(mMenuInfo.id);
item.setTag(mMenuInfo);
item.setOnClickListener(this);
bottomLayout.addView(item, lp);

iv = new ImageView(mActivity);
iv.setBackgroundResource(mMenuInfo.downImg);
item.addView(iv, llp);

tv = new TextView(mActivity);
tv.setText(mMenuInfo.text);
tv.setTextSize(13);
tv.setTextColor(textDown);
item.addView(tv, llp);
}
}

private void setClickAt(int nowId) {
downClick(oldId);
upClick(nowId);
this.oldId = nowId;
}

private void defClick(int id) {
setClickAt(id);
MenuInfo mMenuInfo = (MenuInfo) this.findViewById(id).getTag();
mActivity.getFragmentManager().beginTransaction()
.add(0x9527, mMenuInfo.f, mMenuInfo.id + "").commit();
}

private void downClick(int id) {
LinearLayout ll = (LinearLayout) this.findViewById(id);
MenuInfo mMenuInfo = (MenuInfo) ll.getTag();
ImageView iv = (ImageView) ll.getChildAt(0);
iv.setBackgroundResource(mMenuInfo.downImg);
TextView tv = (TextView) ll.getChildAt(1);
tv.setTextColor(textUp);
}

private void upClick(int id) {
LinearLayout ll = (LinearLayout) this.findViewById(id);
MenuInfo mMenuInfo = (MenuInfo) ll.getTag();
ImageView iv = (ImageView) ll.getChildAt(0);
iv.setBackgroundResource(mMenuInfo.upImg);
TextView tv = (TextView) ll.getChildAt(1);
tv.setTextColor(textDown);
}

@Override
public void onClick(View v) {
int id = v.getId();
setClickAt(id);
MenuInfo mMenuInfo = (MenuInfo) this.findViewById(id).getTag();
FragmentTransaction transaction = mActivity.getFragmentManager().beginTransaction();
transaction.replace(0x9527, mMenuInfo.f);
//		Toast.makeText(mActivity, mActivity.getFragmentManager().getBackStackEntryCount()+"", 0).show();
//		transaction.addToBackStack(null);
transaction.commit();
}
}

好了，没错，看上去就这么多。省去了所有的配置文件，主要的代码就这样完成了。我们看下效果图。