android引用自定义View

1.fragment相当于一个组件，在主activity中引用fragment

如MainActivity的代码如下：

</pre><pre name="code" class="java"><span style="font-family:Times New Roman;font-size:14px;">package com.ahuiapp.myview;import android.support.v7.app.ActionBarActivity;import android.support.v7.app.ActionBar;import android.support.v4.app.Fragment;import android.os.Bundle;import android.view.LayoutInflater;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.ViewGroup;import android.os.Build;public class MainActivity extends ActionBarActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);<span style="white-space:pre"></span>setContentView(R.layout.activity_main); //在activity中默认显示布局setContentView(R.layout.activity_main);          if (savedInstanceState == null) {           getSupportFragmentManager().beginTransaction()                  .add(R.id.container, new PlaceholderFragment())                  .commit(); //在activity中加入fragment，这部分基本是固定的写法        }            @Override    public boolean onCreateOptionsMenu(Menu menu) {                // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.main, menu);        return true;    }    @Override    public boolean onOptionsItemSelected(MenuItem item) {        // Handle action bar item clicks here. The action bar will        // automatically handle clicks on the Home/Up button, so long        // as you specify a parent activity in AndroidManifest.xml.        int id = item.getItemId();        if (id == R.id.action_settings) {            return true;        }        return super.onOptionsItemSelected(item);    }    /**     * A placeholder fragment containing a simple view.     */    public static class PlaceholderFragment extends Fragment {        public PlaceholderFragment() {        }        @Override        public View onCreateView(LayoutInflater inflater, ViewGroup container,                Bundle savedInstanceState) {            View rootView = inflater.inflate(R.layout.fragment_main, container, false);            return rootView;        }    }}</span>

<span style="font-family:Times New Roman;font-size:14px;">//上述是创建工程时自动生成的代码，使用的是新版的ADT，里面会自动创建activity_main.xml和Fragment_main.xml文件，并在MainActivity.java文件中调用。</span>

2.在activity中引用自定义的view(创建一个新的java文件，在java文件中实现绘图等功能代码)
有两种方法：
第一种：将自定义view嵌入到xml文件中，让java文件调用这个xml文件中就行了。
比如将自定义的view加入fragment中，此时的fragment.xml文件如下：

<span style="font-family:Times New Roman;font-size:14px;"> <RelativeLayout  //将自定义的view包完整路径加入到fragment_main.xml的RelativeLayout标签中   <com.ahuiapp.myview.MyView        android:layout_width="wrap_content"        android:layout_height="wrap_content" /></RelativeLayout></span>

此时的MainActivity.java文件如下：

<span style="font-family:Times New Roman;font-size:14px;">//显示默认的布局文件是activity_main.xmlsetContentView(R.layout.activity_main);        //添加的fragment到主activity       if (savedInstanceState == null) {            getSupportFragmentManager().beginTransaction()                    .add(R.id.container, new PlaceholderFragment())                    .commit();        }    }</span>

第二种方法：将自定义view直接设置为默认的显示界面，将默认显示的布局文件注释掉
此时的activity_main.java代码如下：

<span style="font-family:Times New Roman;font-size:14px;">    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);//setContentView(R.layout.activity_main);   MyView myview=new MyView(this,null);   this.setContentView(myview);            //默认显示自定义的view，不显示fragment        //        if (savedInstanceState == null) {//            getSupportFragmentManager().beginTransaction()//                    .add(R.id.container, new PlaceholderFragment())//                    .commit();        }</span>