Java 命令行交互输入库 JLine

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1.作用

通过写java代码，实现自己想要定义的命令，并且也可以实现按Tab键命令补全，help命令功能，退出程序功能。

2.需要的jar包

jar包的CSDN的下载地址

jar包名	说明
jline-3.6.2.jar	提供命令行开发需要的类和方法(核心jar包)

因为在windows上需要用到系统的dll文件（动态链接库），所以还需要下面五个jar包:

jar包名	说明
jansi-1.17.jar	Jansi是一个用于生成和解释ANSI转义序列的java库
jna-4.2.2.jar	Java本机访问
jsr305-3.0.2.jar	Findbugs的JSR305注释
juniversalchardet-1.0.3.jar	Java编码检测器库
sshd-core-1.4.0.jar

3.搭建一个最基础的框架

(1)计算机上的虚拟终端

Terminal terminal = TerminalBuilder.builder().system(true).build();

代码	说明
TerminalBuilder	TerminalBuilder类，创建终端的生成器类
.builder()	返回new TerminalBuilder()
.system(true)	给TerminalBuilder类中的system赋值并返回TerminalBuilder类
.build()	调用TerminalBuilder类中的build()方法获取Terminal 并返回Terminal

(2)通过输入从控制台读取行

LineReader lineReader = LineReaderBuilder.builder().terminal(terminal).build();

代码	说明
LineReaderBuilder	LineReaderBuilder 类
.builder()	返回new LineReaderBuilder ()
.terminal(terminal)	给LineReaderBuilder 类中的terminal赋值并返回LineReaderBuilder 类
.build()	返回LineReader

(3)原样输出输入的内容的demo

public static void main(String[] args) {try {Terminal terminal = TerminalBuilder.builder().system(true).build();LineReader lineReader = LineReaderBuilder.builder().terminal(terminal).build();String prompt = "demo > "; // 输入命令提示信息// 用while死循环，可以在执行完命令后不退出程序，可以继续输入命令while (true) {String line = lineReader.readLine(prompt); // 获取输入的信息System.out.println("输入的命令是：" + line); // 输出输入的信息}} catch (Exception e) {e.printStackTrace();}
}

执行结果如下：

demo > a
输入的命令是：a
demo > b
输入的命令是：b
demo >

4.执行命令

把输入的命令解析成的list传进需要执行命令的方法中，逐个取值，通过switch判断需要执行哪个方法，依次执行。

public static void main(String[] args) {try {Terminal terminal = TerminalBuilder.builder().system(true).build();LineReader lineReader = LineReaderBuilder.builder().terminal(terminal).build();String prompt = "demo > ";while (true) {String line = lineReader.readLine(prompt);System.out.println("输入的命令是：" + line);if (null == line) {continue;}line = line.trim();if (!line.isEmpty()) {ParsedLine parsedLine = lineReader.getParsedLine(); // 解析输入的命令if (null == parsedLine) {continue;}List<String> words = parsedLine.words(); // 获取输入的命令解析成的listSystem.out.println("解析命令生成的list为：" + words);Demo.executeCommand(words); // 执行命令}}} catch (Exception e) {e.printStackTrace();}
}public static void executeCommand(List<String> commands) throws Exception {switch (commands.get(0)) {case "schema":if (commands.size() >= 2) {Demo.schemaCommand(commands);} else {System.out.println("schema命令");}break;case "table":if (commands.size() >= 2) {Demo.tableCommand(commands);} else {System.out.println("table命令");}break;case "help":System.out.println("帮助");break;case "quit":System.out.println("退出程序");System.exit(0);break;default:System.out.println("不支持该命令");}
}public static void schemaCommand(List<String> commands) throws Exception {switch (commands.get(1)) {case "select":System.out.println("查询schema");break;case "update":System.out.println("修改schema");break;default:System.out.println("不支持该命令");}
}public static void tableCommand(List<String> commands) throws Exception {switch (commands.get(1)) {case "select":System.out.println("查询表");break;case "update":System.out.println("修改表");break;default:System.out.println("不支持该命令");}
}

执行结果如下：

demo > schema select
输入的命令是：schema select
解析命令生成的list为：[schema, select]
查询schema
demo > schema update
输入的命令是：schema update
解析命令生成的list为：[schema, update]
修改schema
demo > table select
输入的命令是：table select
解析命令生成的list为：[table, select]
查询表
demo > help
输入的命令是：help
解析命令生成的list为：[help]
帮助
demo > quit
输入的命令是：quit
解析命令生成的list为：[quit]
退出程序

5.help命令

把所有命令放到list里面，执行help命令时，输出list中的内容

public static void executeCommand(List<String> commands) throws Exception {switch (commands.get(0)) {case "schema":if (commands.size() >= 2) {Demo.schemaCommand(commands);} else {System.out.println("schema命令");}break;case "table":if (commands.size() >= 2) {Demo.tableCommand(commands);} else {System.out.println("table命令");}break;case "help":System.out.println("帮助");List<Command> commandList = getCommandList();for (int i = 0; i < commandList.size(); i++) {System.out.print(commandList.get(i).getCommand());System.out.println(commandList.get(i).getDescription());List<Command> childCommandList = commandList.get(i).getChildCommandList();if (null != childCommandList) {for (int j = 0; j < childCommandList.size(); j++) {System.out.print("    " + childCommandList.get(j).getCommand());System.out.println(childCommandList.get(j).getDescription());}}}break;case "quit":System.out.println("退出程序");System.exit(0);break;default:System.out.println("不支持该命令");}
}public static List<Command> getCommandList() throws Exception {List<Command> commandList = new ArrayList<Command>();List<Command> schemaCommandList = new ArrayList<Command>();schemaCommandList.add(new Command("select", "查询模式", null));schemaCommandList.add(new Command("update", "修改模式", null));commandList.add(new Command("schema", "操作模式", schemaCommandList));List<Command> tableCommandList = new ArrayList<Command>();tableCommandList.add(new Command("select", "查询表", null));tableCommandList.add(new Command("update", "修改表", null));commandList.add(new Command("table", "操作表", tableCommandList));commandList.add(new Command("help", "帮助", null));commandList.add(new Command("quit", "退出程序", null));return commandList;
}

Command对象类

public class Command {private String command;private String description;private List<Command> childCommandList;public String getCommand() {return command;}public void setCommand(String command) {this.command = command;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}public List<Command> getChildCommandList() {return childCommandList;}public void setChildCommandList(List<Command> childCommandList) {this.childCommandList = childCommandList;}public Command(String command, String description, List<Command> childCommandList) {this.command = command;this.description = description;this.childCommandList = childCommandList;}
}

执行结果如下：

demo > help
输入的命令是：help
解析命令生成的list为：[help]
帮助
schema操作模式select查询模式update修改模式
table操作表select查询表update修改表
help帮助
quit退出程序
demo > quit
输入的命令是：quit
解析命令生成的list为：[quit]
退出程序

6.Tab命令补全

tab命令补全只需要在初始化LineReader类的时候添加上即可。
由原来的

LineReader lineReader = LineReaderBuilder.builder().terminal(terminal).build();

改为

LineReader lineReader = LineReaderBuilder.builder().terminal(terminal).completer(Demo.getCompleter()).build();

getCompleter()方法相关代码如下：

private static Completer getCompleter() {Completer completer = new AggregateCompleter(getSchemaCompleter(),getTableCompleter(),getHelpCompleter(),getQuitCompleter());return completer;
}private static  Completer getSchemaCompleter() {Completer schemaCompleter = new TreeCompleter(node("schema",node("select", node(NullCompleter.INSTANCE)),node("update", node(NullCompleter.INSTANCE))));return schemaCompleter;
}private static Completer getTableCompleter() {Completer tableCompleter = new TreeCompleter(node("table",node("select", node(NullCompleter.INSTANCE)),node("update", node(NullCompleter.INSTANCE))));return tableCompleter;
}private static Completer getHelpCompleter() {return new ArgumentCompleter(new StringsCompleter("help"), NullCompleter.INSTANCE);
}private static Completer getQuitCompleter() {return new ArgumentCompleter(new StringsCompleter("quit"), NullCompleter.INSTANCE);
}

StringsCompleter 只能实现一个单词的补全
ArgumentCompleter 补全整条命令
AggregateCompleter将多种可能的补全方式组合到一起
TreeCompleter是树形的集合，node添加子命令
ArgumentCompleter 相当于串联电路，而 AggregateCompleter 相当于并联电路

7.输入密码不显示但能获取到密码(ReadPassword)

java.io.Console类可以不回显输入的密码
我用的eclipse，因为eclipse没有主控制台console，所以取不到console，System.console()只能是null
程序打包之后是可以正常用的

public static void main(String[] args) {Console console = System.console();if (console != null) {String name = console.readLine("input name: ");char[] password = console.readPassword("input password: ");String pwd = new String(password);System.out.println("name = " + name + "  password = " + pwd);}
}