点到线段的最短距离
Java code
Java code
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
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);