自定义RelativeLayout view实现布局。

在开发中，一个界面或者几个界面通常用到的基本UI都是相似的。这时候如果布局文件的话 往往会涉及到多个布局文件。我们更倾向于自定义的view。
UI：


public class WFFE_FilePickerView2 extends RelativeLayout implements WFIFormElementActivityResult{
private TextView mTxtTitle;
private ImageView mImgIcon;
private TextView mTxtValue;
private ImageView mImgArrow;
private WFFE_FilePicker2 element;

private static final int ID_TITLE_LABEL = 0x1001;
private static final int ID_RIGHT_ARROW = 0x1002;
private static final int ID_MIDDEL_IMG = 0x1003;
private static final int ID_VALUE_TXT = 0x1004;

public WFFE_FilePickerView2(Context context, WFFE_FilePicker2 filePicker) {
super(context);
this.element = filePicker;
this.initAttributes();
}

public WFFE_FilePickerView2(Context context, AttributeSet attrs) {
super(context, attrs);
}

@SuppressWarnings("ResourceType")
private void initAttributes() {
if (null == getContext() || null == element) {
return;
}

final int imgWidth = GlobalUtil.getPixelsByDp(getContext(), 20.0F);

//
// initializes this ViewGroup and all child views
//
LinearLayout.LayoutParams viewGroupLayoutParams = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT);

ViewUtils.setMarginParams(
this.getContext(),
viewGroupLayoutParams,
true,
WFIFormElement.MARGIN_12DP,
WFIFormElement.MARGIN_5DP,
WFIFormElement.MARGIN_12DP,
WFIFormElement.MARGIN_5DP);

this.setLayoutParams(viewGroupLayoutParams);
this.setGravity(Gravity.CENTER_VERTICAL);

mImgArrow = new ImageView(getContext());
mImgArrow.setId(ID_RIGHT_ARROW);
mImgArrow.setImageResource(R.drawable.icon_right_arrow);
LayoutParams arrowParams = new LayoutParams(imgWidth, imgWidth);
arrowParams.addRule(ALIGN_PARENT_RIGHT);
arrowParams.addRule(CENTER_VERTICAL);
ViewUtils.setMarginParams(getContext(), arrowParams, true, WFIFormElement.MARGIN_5DP, 0, 0, 0);

mTxtTitle = new TextView(getContext());
mTxtTitle.setId(ID_TITLE_LABEL);
mTxtTitle.setTextSize(WFIFormElement.TEXT_SIZE_15SP);
LayoutParams titleParam = new LayoutParams(LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
titleParam.addRule(ALIGN_PARENT_LEFT);
CharSequence titleText = GlobalUtil.appendHeadAsterisk(getContext(), element.isRequired(), element.label, Constants.GREEN);
mTxtTitle.setText(titleText);

mTxtValue = new TextView(getContext());
mTxtValue.setId(ID_VALUE_TXT);
LayoutParams valueParam = new LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
valueParam.addRule(LEFT_OF, mImgArrow.getId());
mTxtValue.setGravity(Gravity.RIGHT);
mTxtValue.setVisibility(GONE);

mImgIcon = new ImageView(getContext());
mImgIcon.setId(ID_MIDDEL_IMG);
LayoutParams iconParam = new LayoutParams(imgWidth, imgWidth);
iconParam.addRule(LEFT_OF, mTxtValue.getId());
mImgIcon.setImageResource(R.drawable.icon_right_arrow);
ViewUtils.setMarginParams(getContext(), iconParam, true, WFIFormElement.MARGIN_5DP, 0, WFIFormElement.MARGIN_5DP, 0);
mImgIcon.setVisibility(GONE);

View lineView = new View(getContext());
lineView.setBackgroundColor(Constants.GREEN);
LayoutParams lineParam = new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 1);
lineParam.setMargins(WFIFormElement.MARGIN_5DP, WFIFormElement.MARGIN_5DP,
WFIFormElement.MARGIN_5DP, WFIFormElement.MARGIN_5DP);
lineParam.addRule(BELOW, mTxtTitle.getId());

this.addView(mTxtTitle, titleParam);
this.addView(mImgIcon, iconParam);
this.addView(mTxtValue, valueParam);
this.addView(mImgArrow, arrowParams);
this.addView(lineView, lineParam);
setupListener();
}

private void setupListener() {
if (null != mImgArrow && mImgArrow.getVisibility() == VISIBLE) {
mImgArrow.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
intentToFilePickerPage();
}
});
}
}

private void intentToFilePickerPage() {
Intent intent = new Intent(getContext(), BM_ContentChooserActivity.class);
intent.putExtra(BM_ContentChooserFragment.FILE_TYPE, BM_ContentChooserFragment.TypeFlag.FORM);
intent.putExtra(BM_ContentChooserFragment.CONTENT_SELECTED_ONE, true);
((Activity) getContext()).startActivityForResult(intent, 1001);
}

@Override
public void handleActivityResult(int requestCode, int resultCode, Intent data) {
if (element.showIcon) {
this.mImgIcon.setVisibility(VISIBLE);
}
FileRecord fileRecord = (FileRecord) data.getSerializableExtra(BM_ContentChooserFragment.SELECTED_FILERECORD);
if (element.showValue) {
this.mTxtValue.setVisibility(VISIBLE);
this.mTxtValue.setText(fileRecord.name);
}
}
}开发中我们的习惯是（至少我的习惯是）：定义一个view 比如说 label  img text img。习惯是从左往右按顺序定义。这样的话 有时候很多UI不能实现。