Android中在EditText输入ip地址

先是布局文件，如下图所示：

<RelativeLayout
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:gravity="center_horizontal"
	>
	<EditText 
		android:id="@+id/local_gw_edit_1"
		android:layout_width="50dp"
		android:layout_height="wrap_content"
		android:textColor="#000"
		android:textSize="15sp"
		android:layout_marginTop="25dp"
		android:gravity="bottom"
		android:singleLine="true"
		android:inputType="number"
		android:maxLength="3"
		android:background="@drawable/login_editbox"
		android:hint="@string/default_gw_hint"/>
	<TextView
		android:id="@+id/dot_1"
		android:layout_toRightOf="@id/local_gw_edit_1"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:text="@string/dot_tv"
		android:layout_marginTop="25dp"
		android:textColor="#000"
		android:textSize="20sp"
		android:textStyle="bold"
		android:singleLine="true"
		android:layout_alignBottom="@id/local_gw_edit_1"
		/>
	<EditText 
		android:id="@+id/local_gw_edit_2"
		android:layout_toRightOf="@id/dot_1"
		android:layout_width="50dp"
		android:layout_height="wrap_content"
		android:textColor="#000"
		android:textSize="15sp"
		android:layout_marginTop="25dp"
		android:gravity="bottom"
		android:singleLine="true"
		android:inputType="number"
		android:maxLength="3"
		android:background="@drawable/login_editbox"
		android:hint="@string/default_gw_hint"/>
	<TextView
		android:id="@+id/dot_2"
		android:layout_toRightOf="@id/local_gw_edit_2"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:text="@string/dot_tv"
		android:layout_marginTop="25dp"
		android:textColor="#000"
		android:textSize="20sp"
		android:textStyle="bold"
		android:singleLine="true"
		android:layout_alignBottom="@id/local_gw_edit_1"
		/>
	<EditText 
		android:id="@+id/local_gw_edit_3"
		android:layout_toRightOf="@id/dot_2"
		android:layout_width="50dp"
		android:layout_height="wrap_content"
		android:textColor="#000"
		android:textSize="15sp"
		android:layout_marginTop="25dp"
		android:gravity="bottom"
		android:singleLine="true"
		android:inputType="number"
		android:maxLength="3"
		android:background="@drawable/login_editbox"
		android:hint="@string/default_gw_hint"/>
	<TextView
		android:id="@+id/dot_3"
		android:layout_toRightOf="@id/local_gw_edit_3"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:text="@string/dot_tv"
		android:layout_marginTop="25dp"
		android:textColor="#000"
		android:textSize="20sp"
		android:textStyle="bold"
		android:singleLine="true"
		android:layout_alignBottom="@id/local_gw_edit_1"
		/>
	<EditText 
		android:id="@+id/local_gw_edit_4"
		android:layout_toRightOf="@id/dot_3"
		android:layout_width="50dp"
		android:layout_height="wrap_content"
		android:textColor="#000"
		android:textSize="15sp"
		android:layout_marginTop="25dp"
		android:gravity="bottom"
		android:singleLine="true"
		android:inputType="number"
		android:maxLength="3"
		android:background="@drawable/login_editbox"
		android:hint="@string/default_gw_hint"/>
</RelativeLayout>
<RelativeLayout 
	android:layout_width="fill_parent"
	android:layout_height="wrap_content"
	android:layout_marginTop="20dp"
	android:layout_marginBottom="20dp"
	android:id="@+id/btn_layout"
	>
   
	<Button
		android:id="@+id/register_btn"
		android:layout_width="90dp"
		android:layout_height="40dp"
		android:layout_marginRight="20dp"
		android:layout_alignParentRight="true"
		android:text="@string/btn_ok"
		android:background="@drawable/btn_style_green"
		android:textColor="#ffffff"
		android:textSize="18sp"
		android:onClick="onOKClick"
		/>
	 
</RelativeLayout>

对于ip地址是分为4个EditText来实现，每一个EditText的最大输入长度均为3，输入类型都是数字。

在Activity中主要是运用TextWatcher来实现对EditText内容的监测，监测输入内容的长度，当前面的EditText的输入长度为3时，后面的EditText自动获取焦点；当后一EditText的内容为0时，前一个EditText自动获取焦点，原理就是这样，

代码如下

class MyTextWatcher implements TextWatcher
{
	public EditText mEditText;
	
	public MyTextWatcher(EditText mEditText) {
		super();
		this.mEditText = mEditText;
	}

	@Override
	public void afterTextChanged(Editable s) {
		// TODO Auto-generated method stub
		if(s.length() == 3)
		{
			if(this.mEditText == gwEdit[0])
			{
				gwEdit[1].requestFocus();
			}
			else if(this.mEditText == gwEdit[1])
			{
				gwEdit[2].requestFocus();
			}
			else if(this.mEditText == gwEdit[2])
			{
				gwEdit[3].requestFocus();
			}
		}
		else if(s.length() == 0)
		{
			if(this.mEditText == gwEdit[3])
			{
				gwEdit[2].requestFocus();
			}
			else if(this.mEditText == gwEdit[2])
			{
				gwEdit[1].requestFocus();
			}
			else if(this.mEditText == gwEdit[1])
			{
				gwEdit[0].requestFocus();
			}
		}
		
	}

	@Override
	public void beforeTextChanged(CharSequence s, int start, int count,
			int after) {
		// TODO Auto-generated method stub
		
	}

	@Override
	public void onTextChanged(CharSequence s, int start, int before,
			int count) {
		// TODO Auto-generated method stub
		
	}
	
}

给每一个EditText加上TextWatcher监听器就可以了

private MyTextWatcher[] mTextWatcher = new MyTextWatcher[4];
for(int i = 0; i < GW_NUMBER; i++)
{
	gwEdit[i] = (EditText)findViewById(mIDs[i]);
	mTextWatcher[i] = new MyTextWatcher(gwEdit[i]);
	gwEdit[i].addTextChangedListener(mTextWatcher[i]);
}

至此完工。。。