android 使用Builder模式 构建自定义title

1.简介

android开发中，每个页面中都有一些特定或者通用的title样式。如果我们分别跟每个页面去设置布局再进行逻辑处理。会很冗余，而且开发的效率也会大大降低。今天就跟大家介绍一种使用Builder模式来构建自定义title的方法。

2.定义布局

首先我们应该大致写一下我们需要的title的通用布局。下面就以我项目中用到的为例。贴出代码：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/rl_titlebar"    android:layout_width="match_parent"    android:layout_height="48dp"    android:background="@color/bg_agray"    android:fitsSystemWindows="true"    android:orientation="horizontal" >    <ImageView        android:id="@+id/titlebar_iv_left"        android:layout_width="48dp"        android:layout_height="match_parent"        android:layout_centerVertical="true"        android:padding="12dp"        android:visibility="gone" />    <TextView        android:id="@+id/titlebar_tv_left"        android:layout_width="wrap_content"        android:layout_height="match_parent"        android:gravity="center_vertical"        android:paddingLeft="16dp"        android:paddingRight="16dp"          android:textColor="@drawable/txtcolor_oran2alpha_sel"        android:textSize="16sp"        android:visibility="gone" />    <TextView        android:id="@+id/titlebar_tv"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:singleLine="true"        android:textSize="16sp"        android:textColor="@color/txt_black"        android:marqueeRepeatLimit="marquee_forever"        android:ellipsize="marquee"        android:layout_centerInParent="true"        android:gravity="center"        android:maxWidth="224dp" />    <ImageView        android:id="@+id/titlebar_iv_right"        android:layout_width="48dp"        android:layout_height="match_parent"        android:layout_alignParentRight="true"        android:layout_centerVertical="true"        android:padding="12dp"        android:visibility="gone" />    <TextView        android:id="@+id/titlebar_tv_right"        android:layout_width="wrap_content"        android:layout_height="match_parent"        android:layout_alignParentRight="true"        android:gravity="center_vertical"        android:paddingLeft="16dp"        android:paddingRight="16dp"          android:textColor="@drawable/txtcolor_oran2alpha_sel"        android:textSize="16sp"        android:visibility="gone" /></RelativeLayout>

我的项目中title会有左右两边显示图片或者文字和显示中间的标题的需求。

3.构建TitleBuilder类

使用Builder设计模式构建TitleBuilder类，声明上述布局中的View。

public class TitleBuilder {    private View viewTitle;    private TextView tvTitle;    private ImageView ivLeft;    private ImageView ivRight;    private TextView tvLeft;    private TextView tvRight;    public TitleBuilder(Activity context) {        viewTitle = context.findViewById(R.id.rl_titlebar);        tvTitle = (TextView) viewTitle.findViewById(R.id.titlebar_tv);        ivLeft = (ImageView) viewTitle.findViewById(R.id.titlebar_iv_left);        ivRight = (ImageView) viewTitle.findViewById(R.id.titlebar_iv_right);        tvLeft = (TextView) viewTitle.findViewById(R.id.titlebar_tv_left);        tvRight = (TextView) viewTitle.findViewById(R.id.titlebar_tv_right);    }    public TitleBuilder(View context) {        viewTitle = context.findViewById(R.id.rl_titlebar);        tvTitle = (TextView) viewTitle.findViewById(R.id.titlebar_tv);        ivLeft = (ImageView) viewTitle.findViewById(R.id.titlebar_iv_left);        ivRight = (ImageView) viewTitle.findViewById(R.id.titlebar_iv_right);        tvLeft = (TextView) viewTitle.findViewById(R.id.titlebar_tv_left);        tvRight = (TextView) viewTitle.findViewById(R.id.titlebar_tv_right);    }    //title    public TitleBuilder setTitleBgRes(int resId) {        viewTitle.setBackgroundResource(resId);        return this;    }    public TitleBuilder setTitleText(String text) {        tvTitle.setVisibility(TextUtils.isEmpty(text) ? View.GONE : View.VISIBLE);        tvTitle.setText(text);        return this;    }    //left    public TitleBuilder setLeftImage(int resId) {        ivLeft.setVisibility(resId > 0 ? View.VISIBLE : View.GONE);        ivLeft.setImageResource(resId);        return this;    }    public TitleBuilder setLeftText(String text) {        tvLeft.setVisibility(TextUtils.isEmpty(text) ? View.GONE : View.VISIBLE);        tvLeft.setText(text);        return this;    }    public TitleBuilder setLeftClickListener(OnClickListener listener) {        if (ivLeft.getVisibility() == View.VISIBLE) {            ivLeft.setOnClickListener(listener);        } else if (tvLeft.getVisibility() == View.VISIBLE) {            tvLeft.setOnClickListener(listener);        }        return this;    }    //right    public TitleBuilder setRightImage(int resId) {        ivRight.setVisibility(resId > 0 ? View.VISIBLE : View.GONE);        ivRight.setImageResource(resId);        return this;    }    public TitleBuilder setRightText(String text) {        tvRight.setVisibility(TextUtils.isEmpty(text) ? View.GONE : View.VISIBLE);        tvRight.setText(text);        return this;    }    public TitleBuilder setRightOnclickListener(OnClickListener listener) {        if (ivRight.getVisibility() == View.VISIBLE) {            ivRight.setOnClickListener(listener);        } else if (tvRight.getVisibility() == View.VISIBLE) {            tvRight.setOnClickListener(listener);        }        return this;    }    public View build() {        return viewTitle;    }}

4.如何使用

到了这里准备工作已经完成，下面就该演示如何使用：
首先在要加入title的布局中include上述布局：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"      android:layout_width="match_parent"      android:layout_height="match_parent"      android:orientation="vertical">    <include layout="@layout/titlebar"/>    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center"        android:text="Set TitleBar"/></LinearLayout>

然后在代码中就可以直接使用了：

    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.layout_title);        initView();    }    private void initView() {        new TitleBuilder(this).setTitleText("Title").setLeftText("Left").setRightText("Right").setLeftClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {            }        }).setRightOnclickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {            }        }).build();    }

根据页面的需求可以动态的设置左右两边显示文字图片，或者隐藏，非常的方便。