1.模式定义：
提供一种方法顺序访问一个容器中的各个元素，而又不需要暴露该对象的内部显示(如List,Objcet数组，set)。
首先看下简单的使用
一般写法:比如百度网盘登录可以用微信和qq，假设qq使用的是List保存数据，和微信使用的是数组保存数据
用户信息
public class UserInfo {
public String userName;
public String userPwd;
public String userId;
public String userSex;
public UserInfo(String userName, String userPwd, String userId, String userSex) {
this.userName = userName;
this.userPwd = userPwd;
this.userId = userId;
this.userSex = userSex;
}
@Override
public String toString() {
return "UserInfo{" +
"userName='" + userName + '\'' +
", userPwd='" + userPwd + '\'' +
", userId='" + userId + '\'' +
", userSex='" + userSex + '\'' +
'}';
}
}
QQUserSystem用户系统
public class QQUserSystem {
private List<UserInfo> userInfos;
public QQUserSystem() {
userInfos = new ArrayList<>();
userInfos.add(new UserInfo("Peakmain","1234","001","男"));
userInfos.add(new UserInfo("Treasure","1234","002","女"));
userInfos.add(new UserInfo("Jack","abcd","003","男"));
}
public List<UserInfo> getUserInfos() {
return userInfos;
}
}微信用户系统
public class WXUserSystem {
private UserInfo[] userInfos;
public WXUserSystem() {
userInfos = new UserInfo[3];
userInfos[0] = new UserInfo("奋斗@加油", "1234", "001", "男");
userInfos[1] = new UserInfo("芊芊", "1234", "002", "女");
userInfos[2] = new UserInfo("太想爱你", "1234", "003", "男");
}
public UserInfo[] getUserInfos() {
return userInfos;
}
}测试
public class Client {
public static void main(String[] args) {
UserInfo userInfo=queryWXUserInfo("爱我的你","1234");
if(userInfo==null){
userInfo=queryQQUserInfo("爱我的你","1234");
}
if(userInfo==null){
System.out.println("查无此人");
}
}
private static UserInfo queryQQUserInfo(String name, String pwd) {
QQUserSystem userSystem=new QQUserSystem();
List<UserInfo> userInfos = userSystem.getUserInfos();
for (UserInfo userInfo : userInfos) {
if(userInfo.userName.equals(name)&&userInfo.userPwd.equals(pwd)){
return userInfo;
}
}
return null;
}
/**
* 查询微信用户信息
*/
private static UserInfo queryWXUserInfo(String name, String password) {
WXUserSystem userSystem=new WXUserSystem();
UserInfo[] userInfos = userSystem.getUserInfos();
for (UserInfo userInfo : userInfos) {
if(userInfo.userName.equals(name)&&userInfo.userPwd.equals(password)){
return userInfo;
}
}
return null;
}
}
这时候我们将用户信息以 List userInfos或者数组 UserInfo[] userInfos暴露在外面，这时候我们可以使用迭代器
责任链模式构建用户系统
迭代器接口
public interface Iterator<T> {
/**
* 获取下一个
*/
T next();
/**
* 是否有下一个
*/
boolean hasNext();
}QQIterator迭代器
public class QQIterator implements Iterator<UserInfo> {
List<UserInfo> userInfos;
int index = 0;//下标
public QQIterator(List<UserInfo> userInfos) {
this.userInfos = userInfos;
}
@Override
public UserInfo next() {
return userInfos.get(index++);
}
@Override
public boolean hasNext() {
return index<userInfos.size();
}
}
微信迭代器
public class WXIterator implements Iterator<UserInfo> {
UserInfo[] userInfos;
int index=0;
public WXIterator(UserInfo[] userInfos) {
this.userInfos = userInfos;
}
@Override
public UserInfo next() {
return userInfos[index++];
}
@Override
public boolean hasNext() {
return index<userInfos.length;
}
}Aggregate获取迭代器
public interface Aggregate<T> {
//获得迭代器
Iterator<T> iterator();
}修改qq用户系统
public class QQUserSystem implements Aggregate<UserInfo>{
private List<UserInfo> userInfos;
public QQUserSystem() {
userInfos = new ArrayList<>();
userInfos.add(new UserInfo("Peakmain","1234","001","男"));
userInfos.add(new UserInfo("Treasure","1234","002","女"));
userInfos.add(new UserInfo("Jack","abcd","003","男"));
}
//将暴露的List隐藏，显示迭代器
@Override
public Iterator<UserInfo> iterator() {
return new QQIterator(userInfos);
}
}修改微信用户系统
public class WXUserSystem implements Aggregate<UserInfo>{
private UserInfo[] userInfos;
public WXUserSystem() {
userInfos = new UserInfo[3];
userInfos[0] = new UserInfo("奋斗@加油", "1234", "001", "男");
userInfos[1] = new UserInfo("芊芊", "1234", "002", "女");
userInfos[2] = new UserInfo("太想爱你", "1234", "003", "男");
}
@Override
public Iterator<UserInfo> iterator() {
return new WXIterator(userInfos);
}
}测试
public class Client {
public static void main(String[] args) {
QQUserSystem qqUserSystem=new QQUserSystem();
WXUserSystem wxUserSystem=new WXUserSystem();
UserInfo userInfo=queryUserInfo("爱我的你","1234",qqUserSystem.iterator());
if(userInfo==null){
userInfo=queryUserInfo("爱我的你","1234",wxUserSystem.iterator());
}
if(userInfo==null){
System.out.println("查无此人");
}
}
private static UserInfo queryUserInfo(String name, String pwd, Iterator<UserInfo> iterator) {
if(iterator.hasNext()){
UserInfo userInfo = iterator.next();
if(userInfo.userName.equals(name)&&userInfo.userPwd.equals(pwd)){
return userInfo;
}
}
return null;
}
}
构建通用的底部BottomTabNavigationBar
迭代器接口
public interface TabIterator {
boolean hasNext();
BottomTabItem next();
}
列表显示的迭代器
public class TabListIterator<T extends BottomTabItem> implements TabIterator {
private List<T> mTabItems;
private int index;
public TabListIterator() {
this.mTabItems = new ArrayList<>();
}
@Override
public boolean hasNext() {
return index < mTabItems.size();
}
@Override
public BottomTabItem next() {
return mTabItems.get(index++);
}
public void addItem(T item) {
mTabItems.add(item);
}
}底部item的基类
public abstract class BottomTabItem {
private int mLayoutId;
private View mTabItemView;
private Context mContext;
public BottomTabItem(int layoutId, Context context) {
this.mLayoutId = layoutId;
this.mContext = context;
}
/**
* 获取底部条目的显示
*/
public View getTabView() {
if (mTabItemView == null) {
mTabItemView = LayoutInflater.from(mContext).inflate(mLayoutId, null);
initLayout();
}
return mTabItemView;
}
/**
* 初始化显示
*/
public abstract void initLayout();
protected <T extends View> T findViewById(int id) {
return (T) mTabItemView.findViewById(id);
}
/**
* 是否选择当前条目
*/
protected abstract void setSelected(boolean selected);
}
MainBottomTabItem实现类
public class MainBottomTabItem extends BottomTabItem {
private Builder builder;
private MainBottomTabItem(Context context) {
super(R.layout.tab_main_bottom_item, context);
}
public MainBottomTabItem(Builder builder) {
this(builder.mContext);
this.builder=builder;
}
@Override
public void initLayout() {
TextView tabText = findViewById(R.id.tab_text);
ImageView tabIcon = findViewById(R.id.tab_icon);
if (!TextUtils.isEmpty(builder.mText)) {
tabText.setText(builder.mText);
}
if (builder.mIcon != 0) {
tabIcon.setImageResource(builder.mIcon);
}
}
@Override
protected void setSelected(boolean selected) {
TextView tabText = findViewById(R.id.tab_text);
ImageView tabIcon = findViewById(R.id.tab_icon);
tabIcon.setSelected(selected);
tabText.setSelected(selected);
}
public static class Builder {
private Context mContext;
private String mText;
private int mIcon;
public Builder setText(String text) {
this.mText = text;
return this;
}
public Builder setIcon(int icon) {
this.mIcon = icon;
return this;
}
public Builder(Context context) {
this.mContext = context;
}
public MainBottomTabItem create() {
return new MainBottomTabItem(this);
}
}
}
每个item的集合
public class TabBottomNavigation extends LinearLayout {
private List<BottomTabItem> mTabItems;
private int mCurrentPosition = 0;
public TabBottomNavigation(Context context) {
this(context, null);
}
public TabBottomNavigation(Context context, @Nullable AttributeSet attrs) {
this(context, attrs, 0);
}
public TabBottomNavigation(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
setOrientation(HORIZONTAL);
mTabItems = new ArrayList<>();
}
public void addTabItem(TabIterator tabIterator) {
mTabItems.clear();
int index=0;
while (tabIterator.hasNext()) {
BottomTabItem tabItem = tabIterator.next();
View tabView = tabItem.getTabView();
addView(tabView);
//设置weight
LinearLayout.LayoutParams params = (LayoutParams) tabView.getLayoutParams();
params.weight = 1;
params.gravity = Gravity.CENTER;
tabView.setLayoutParams(params);
//设置点击事件
setItemClickListener(tabView,index++);
mTabItems.add(tabItem);
}
//设置默认选中的
mTabItems.get(0).setSelected(true);
}
public void setItemClickListener( View tabView, final int position) {
tabView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
if (mCurrentPosition != position) {
//原本选中的设置为没有选中
mTabItems.get(mCurrentPosition).setSelected(false);
mCurrentPosition=position;
//设置当前的为选中状态
mTabItems.get(mCurrentPosition).setSelected(true);
}
}
});
}
}
测试
public class MainActivity extends AppCompatActivity {
private TabBottomNavigation mTabBottomNavigation;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTabBottomNavigation = (TabBottomNavigation) findViewById(R.id.tab_bottom);
TabListIterator<MainBottomTabItem> listIterator = new TabListIterator<>();
listIterator.addItem(new MainBottomTabItem.Builder(this)
.setIcon(R.drawable.main_tab_item).setText("text1").create());
listIterator.addItem(new MainBottomTabItem.Builder(this)
.setIcon(R.drawable.main_tab_item).setText("text2").create());
listIterator.addItem(new MainBottomTabItem.Builder(this)
.setIcon(R.drawable.main_tab_item).setText("text3").create());
listIterator.addItem(new MainBottomTabItem.Builder(this)
.setIcon(R.drawable.main_tab_item).setText("text4").create());
mTabBottomNavigation.addTabItem(listIterator);
/* List<BottomTabItem> bottomTabItems=new ArrayList<>();
bottomTabItems.add(new MainBottomTabItem.Builder(this).setText("text1").setIcon(R.drawable.main_tab_item).create());
bottomTabItems.add(new MainBottomTabItem.Builder(this).setText("text2").setIcon(R.drawable.main_tab_item).create());
bottomTabItems.add(new MainBottomTabItem.Builder(this).setText("text3").setIcon(R.drawable.main_tab_item).create());
bottomTabItems.add(new MainBottomTabItem.Builder(this).setText("text4").setIcon(R.drawable.main_tab_item).create());
mTabBottom.addTabItem(bottomTabItems*/
}
}
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