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);}@Overridepublic 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。