java源代码实例

点到线段的最短距离

Java code

   

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    private
     
    double
     pointToLine(
    int
     x1, 
    int
     y1, 
    int
     x2, 
    int
     y2, 
    int
     x0, 
    int
     y0) { 
    double
     space 
    =
     
    0
    ; 
    double
     a, b, c; a 
    =
     lineSpace(x1, y1, x2, y2);
    //
     线段的长度
     
     b 
    =
     lineSpace(x1, y1, x0, y0);
    //
     (x1,y1)到点的距离
     
     c 
    =
     lineSpace(x2, y2, x0, y0);
    //
     (x2,y2)到点的距离
     
     
    if
     (c 
    <=
     
    0.000001
     
    ||
     b 
    <=
     
    0.000001
    ) { space 
    =
     
    0
    ; 
    return
     space; } 
    if
     (a 
    <=
     
    0.000001
    ) { space 
    =
     b; 
    return
     space; } 
    if
     (c 
    *
     c 
    >=
     a 
    *
     a 
    +
     b 
    *
     b) { space 
    =
     b; 
    return
     space; } 
    if
     (b 
    *
     b 
    >=
     a 
    *
     a 
    +
     c 
    *
     c) { space 
    =
     c; 
    return
     space; } 
    double
     p 
    =
     (a 
    +
     b 
    +
     c) 
    /
     
    2
    ;
    //
     半周长
     
     
    double
     s 
    =
     Math.sqrt(p 
    *
     (p 
    -
     a) 
    *
     (p 
    -
     b) 
    *
     (p 
    -
     c));
    //
     海伦公式求面积
     
     space 
    =
     
    2
     
    *
     s 
    /
     a;
    //
     返回点到线的距离（利用三角形面积公式求高）
     
     
    return
     space; } 
    //
     计算两点之间的距离
     
     
    private
     
    double
     lineSpace(
    int
     x1, 
    int
     y1, 
    int
     x2, 
    int
     y2) { 
    double
     lineLength 
    =
     
    0
    ; lineLength 
    =
     Math.sqrt((x1 
    -
     x2) 
    *
     (x1 
    -
     x2) 
    +
     (y1 
    -
     y2) 
    *
     (y1 
    -
     y2)); 
    return
     lineLength; } 

   

java各种数据库连接

Java code

   

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     MySQL： String Driver
    =
    "
    com.mysql.jdbc.Driver
    "
    ; 
    //
    驱动程序
     
     String URL
    =
    "
    jdbc:mysql://localhost:3306/db_name
    "
    ; 
    //
    连接的URL,db_name为数据库名 
     
     String Username
    =
    "
    username
    "
    ; 
    //
    用户名
     
     String Password
    =
    "
    password
    "
    ; 
    //
    密码
     
     Class.forName(Driver).
    new
     Instance(); Connection con
    =
    DriverManager.getConnection(URL,Username,Password); Microsoft SQL Server 
    2
    .0驱动(3个jar的那个): String Driver
    =
    "
    com.microsoft.jdbc.sqlserver.SQLServerDriver
    "
    ; 
    //
    连接SQL数据库的方法
     
     String URL
    =
    "
    jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=db_name
    "
    ; 
    //
    db_name为数据库名
     
     String Username
    =
    "
    username
    "
    ; 
    //
    用户名
     
     String Password
    =
    "
    password
    "
    ; 
    //
    密码
     
     Class.forName(Driver).
    new
     Instance(); 
    //
    加载数据可驱动
     
     Connection con
    =
    DriverManager.getConnection(URL,UserName,Password); 
    // 
    Microsoft SQL Server 
    3
    .0驱动(1个jar的那个): 
    //
     老紫竹完善
     
     String Driver
    =
    "
    com.microsoft.sqlserver.jdbc.SQLServerDriver
    "
    ; 
    //
    连接SQL数据库的方法
     
     String URL
    =
    "
    jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=db_name
    "
    ; 
    //
    db_name为数据库名
     
     String Username
    =
    "
    username
    "
    ; 
    //
    用户名
     
     String Password
    =
    "
    password
    "
    ; 
    //
    密码
     
     Class.forName(Driver).
    new
     Instance(); 
    //
    加载数据可驱动
     
     Connection con
    =
    DriverManager.getConnection(URL,UserName,Password); 
    // 
    Sysbase: String Driver
    =
    "
    com.sybase.jdbc.SybDriver
    "
    ; 
    //
    驱动程序
     
     String URL
    =
    "
    jdbc:Sysbase://localhost:5007/db_name
    "
    ; 
    //
    db_name为数据可名
     
     String Username
    =
    "
    username
    "
    ; 
    //
    用户名
     
     String Password
    =
    "
    password
    "
    ; 
    //
    密码
     
     Class.forName(Driver).newInstance(); Connection con
    =
    DriverManager.getConnection(URL,Username,Password); Oracle(用thin模式): String Driver
    =
    "
    oracle.jdbc.driver.OracleDriver
    "
    ; 
    //
    连接数据库的方法
     
     String URL
    =
    "
    jdbc:oracle:thin:@loaclhost:1521:orcl
    "
    ; 
    //
    orcl为数据库的SID
     
     String Username
    =
    "
    username
    "
    ; 
    //
    用户名
     
     String Password
    =
    "
    password
    "
    ; 
    //
    密码
     
     Class.forName(Driver).newInstance(); 
    //
    加载数据库驱动
     
     Connection con
    =
    DriverManager.getConnection(URL,Username,Password); PostgreSQL: String Driver
    =
    "
    org.postgresql.Driver
    "
    ; 
    //
    连接数据库的方法
     
     String URL
    =
    "
    jdbc:postgresql://localhost/db_name
    "
    ; 
    //
    db_name为数据可名
     
     String Username
    =
    "
    username
    "
    ; 
    //
    用户名
     
     String Password
    =
    "
    password
    "
    ; 
    //
    密码
     
     Class.forName(Driver).newInstance(); Connection con
    =
    DriverManager.getConnection(URL,Username,Password); DB2： String Driver
    =
    "
    com.ibm.db2.jdbc.app.DB2.Driver
    "
    ; 
    //
    连接具有DB2客户端的Provider实例 
    //
    String Driver="com.ibm.db2.jdbc.net.DB2.Driver"; 
    //
    连接不具有DB2客户端的Provider实例
     
     String URL
    =
    "
    jdbc:db2://localhost:5000/db_name
    "
    ; 
    //
    db_name为数据可名
     
     String Username
    =
    "
    username
    "
    ; 
    //
    用户名
     
     String Password
    =
    "
    password
    "
    ; 
    //
    密码
     
     Class.forName(Driver).newInstance(); Connection con
    =
    DriverManager.getConnection(URL,Username,Password); Informix: String Driver
    =
    "
    com.informix.jdbc.IfxDriver
    "
    ; String URL
    =
    "
    jdbc:Informix-sqli://localhost:1533/db_name:INFORMIXSER=myserver
    "
    ; 
    //
    db_name为数据可名
     
     String Username
    =
    "
    username
    "
    ; 
    //
    用户名
     
     String Password
    =
    "
    password
    "
    ; 
    //
    密码
     
     Class.forName(Driver).newInstance(); Connection con
    =
    DriverManager.getConnection(URL,Username,Password); JDBC
    -
    ODBC: String Driver
    =
    "
    sun.jdbc.odbc.JdbcOdbcDriver
    "
    ; String URL
    =
    "
    jdbc:odbc:dbsource
    "
    ; 
    //
    dbsource为数据源名
     
     String Username
    =
    "
    username
    "
    ; 
    //
    用户名
     
     String Password
    =
    "
    password
    "
    ; 
    //
    密码
     
     Class.forName(Driver).newInstance(); Connection con
    =
    DriverManager.getConnection(URL,Username,Password);