JDBC(Java DataBase Connectivity) 基础知识
JDBC(Java DataBase Connectivity)是Java程式用來連結資料庫的程式庫(java.sql.*)。其中主要的類別有DriverManager: 用來產生資料庫連線(Connection)
Connection: 用來產生下達命令給資料庫的敘述(Statement, PreparedStatement和CallableStatement)
Statement: 用來下達查詢(executeQuery(), 傳回ResultSet)和更新(executeUpdate(), 傳回整數代表異動的資料數目)命令,
ResultSet: 利用其next()和getXXX()方法抓出查詢的結果
PreparedStatement: 先送出命令的模板, 然後再傳遞所需要的參數
CallableStatement: 呼叫資料庫內的Stored Procedure
DatabaseMetaData: 用來查詢資料庫綱要
下面的JDBCBridgeTest.java說明上面幾種Class的用法
import java.sql.*;
import ncnu.sql.*;
public class JDBCBridgeTest {
public static void main(String[] argv) {
try {
Class.forName ("sun.jdbc.odbc.JdbcOdbcDriver");
String pass = "password";
String db = "jdbc:odbc:ncnu";
if (argv.length>0) {
pass = argv;
}
if (argv.length>1) {
db = argv;
}
Connection con = DriverManager.getConnection (db, "sa", pass);
con.setAutoCommit(true);
PreparedStatement pstmt;
Statement stmt;
ResultSet rs;
stmt = con.createStatement();
int count = 0;
long start = System.currentTimeMillis();
rs = stmt.executeQuery("select courseid,year,class,studentid from selected");
while (rs.next()) {
count++;
rs.getBytes(1);
rs.getBytes(2);
rs.getBytes(3);
rs.getBytes(4);
}
rs.close();
System.out.println("getBytes version for "+count+" rows: "+(System.currentTimeMillis()-start));
start = System.currentTimeMillis();
rs = stmt.executeQuery("select courseid,year,class,studentid from selected");
while (rs.next()) {
SQL.toString(rs.getBytes(1));
SQL.toString(rs.getBytes(2));
SQL.toString(rs.getBytes(3));
SQL.toString(rs.getBytes(4));
}
rs.close();
System.out.println("SQL.toString version for "+count+" rows: "+(System.currentTimeMillis()-start));
start = System.currentTimeMillis();
rs = stmt.executeQuery("select courseid,year,class,studentid from selected");
while (rs.next()) {
rs.getString(1);
rs.getString(2);
rs.getString(3);
rs.getString(4);
}
rs.close();
System.out.println("System getString version for "+count+" rows: "+(System.currentTimeMillis()-start));
stmt.executeUpdate("delete printlog");
con.commit();
start = System.currentTimeMillis();
for (int i=1; i<=10000; i++) {
stmt.executeUpdate("insert printlog(printid,studentid,class,type,copy,year,email,success,ip,price) values("+i+",'90213001','B','中文歷年成績單',1,'901','ssyu@ncnu.edu.tw','Y','163.22.22.22',20)");
con.commit();
}
System.out.println("Statement insert 10000 rows: "+(System.currentTimeMillis()-start));
start = System.currentTimeMillis();
for (int i=1; i<=10000; i++) {
stmt.executeUpdate("delete printlog where printid="+i);
con.commit();
}
System.out.println("Statement delete 10000 rows: "+(System.currentTimeMillis()-start));
stmt.close();
start = System.currentTimeMillis();
pstmt = con.prepareStatement("insert printlog(printid,studentid,class,type,copy,year,email,success,ip,price) values(?,?,?,?,?,?,?,?,?,?)");
for (int i=1;i<=10000; i++) {
pstmt.setInt(1,i);
pstmt.setString(2,"90213001");
pstmt.setString(3,"B");
pstmt.setString(4,"中文歷年成績單");
pstmt.setInt(5,3);
pstmt.setString(6,"901");
pstmt.setString(7,"ssyu@ncnu.edu.tw");
pstmt.setString(8,"Y");
pstmt.setString(9,"163.22.22.22");
pstmt.setInt(10,20);
pstmt.executeUpdate();
con.commit();
}
System.out.println("PreparedStatement version1 insert 10000 rows: "+(System.currentTimeMillis()-start));
pstmt.close();
start = System.currentTimeMillis();
pstmt = con.prepareStatement("delete printlog where printid=?");
for (int i=1; i<=10000; i++) {
pstmt.setInt(1,i);
pstmt.executeUpdate();
con.commit();
}
pstmt.close();
System.out.println("PrepareStatement delete 10000 rows: "+(System.currentTimeMillis()-start));
start = System.currentTimeMillis();
pstmt = con.prepareStatement("insert printlog(printid,studentid,class,type,copy,year,email,success,ip,price) values(?,?,?,?,?,?,?,?,?,?)");
for (int i=1;i<=10000; i++) {
pstmt.setInt(1,i);
pstmt.setBytes(2,SQL.toAscii("90213001"));
pstmt.setBytes(3,SQL.toAscii("B"));
pstmt.setBytes(4,SQL.toAscii("中文歷年成績單"));
pstmt.setInt(5,3);
pstmt.setBytes(6,SQL.toAscii("901"));
pstmt.setBytes(7,SQL.toAscii("ssyu@ncnu.edu.tw"));
pstmt.setBytes(8,SQL.toAscii("N"));
pstmt.setBytes(9,SQL.toAscii("163.22.22.22"));
pstmt.setInt(10,20);
pstmt.executeUpdate();
con.commit();
}
System.out.println("PreparedStatement version2 insert 10000 rows: "+(System.currentTimeMillis()-start));
pstmt.close();
stmt = con.createStatement();
stmt.executeUpdate("delete printlog");
stmt.close();
con.close();
} catch (Exception ex) {
ex.printStackTrace();
System.exit(1);
}
}
}
SQL.java的Source Code如下
package ncnu.sql;
import sun.io.*;
import ncnu.rule.Environment;
/**
* The class is used to work around a bug in JDBC drivers. The driver truncate the leading
* byte of Unicode character before sending to DBMS. This only works for ASCII character.
* To handle strings to DBMS, you have to use SQL.toSQL() to wrap the output
* string. JDBC drivers also treat the data from DBMS as ASCII code by adding 0 before every
* bytes of the incoming data. This also produce errors for Non-ASCII characters. To work
* around this bug, you have to wrap the incoming data with SQL.fromSQL()
*/
public class SQL {
static ByteToCharConverter toChar;
static CharToByteConverter toByte;
static boolean trans = true;
static {
try {
if (System.getProperty("java.version").startsWith("1.1")) {
trans = true;
} else {
trans = false;
}
String encoding = "Big5";
String domain = Environment.getDomain();
if (domain.endsWith(".tw")) {
encoding = "Big5";
}
SQL.toChar = ByteToCharConverter.getConverter(encoding);
SQL.toByte = CharToByteConverter.getConverter(encoding);
} catch(Exception ex) {
ex.printStackTrace();
System.exit(1);
}
}
public static void setEncoding(String encoding) {
try {
SQL.toChar = ByteToCharConverter.getConverter(encoding);
SQL.toByte = CharToByteConverter.getConverter(encoding);
} catch(Exception ex) {}
}
/**
* convert a string to ASCII byte array
*/
public static byte[] toAscii(String s) {
if (s==null) return new byte;
try {
synchronized(toByte) {
return toByte.convertAll(s.toCharArray());
}
} catch(Exception ex) {
System.out.println(ex);
return new byte;
}
}
public static char[] toChars(byte[] data) {
if (data==null) {
return new char;
}
try {
synchronized(toChar) {
return toChar.convertAll(data);
}
} catch(Exception ex) {
System.out.println(ex);
return new char;
}
}
public static String toStringFast(byte[] data) {
if (data==null) {
return "";
}
char[] tmp = new char;
for (int i=0; i<data.length; i++) {
tmp = (char)data;
}
return new String(tmp);
}
public static String quote(String s) {
if (s.indexOf("'")<0) {
return s;
}
StringBuffer sb = new StringBuffer();
for (int i=0; i<s.length(); i++) {
char c = s.charAt(i);
sb.append(c);
if (c=='\'') {
sb.append(c);
}
}
return sb.toString();
}
public static String toString(byte[] data) {
if (data==null) {
return "";
}
try {
synchronized(toChar) {
return new String(toChar.convertAll(data));
}
} catch(Exception ex) {
System.out.println(ex);
return "";
}
}
/**
* Convert a string for output to DBMS
* @param s The string needs to be converted.
* @return A string which will be truncated by JDBC to produce Big5 characters.
*/
public static String toSQL(String s) {
if (s==null) return "";
if (!trans) return s;
byte[] orig;
try {
synchronized(toChar) {
orig = toByte.convertAll(s.toCharArray());
}
char[] dest = new char;
for (int i=0; i < orig.length; i++)
dest = (char)orig;
return new String(dest);
} catch (Exception e) {
e.printStackTrace();
return s;
}
}
/**
* Convert an incorrect string produeced by JDBC drivers to correct Unicode string.
* @param s The string needs to be converted.
* @return A correct Unicode string.
*/
public static String fromSQL(String s) {
int i, j;
if (s==null) return "";
if (!trans) return s;
char[] orig = s.toCharArray();
byte[] dest = new byte;
for (i=0; i < orig.length; i++)
dest = (byte) orig;
try {
synchronized(toChar) {
char[] tmp = toChar.convertAll(dest);
return new String(tmp);
}
} catch (Exception e) {
e.printStackTrace();
return s;
}
}
}
查詢資料庫綱要
package ncnu.sql;
/* Program Name: Schema.java
Subject: 資料綱要讀取程式
Author: 俞旭昇 Shiuh-Sheng Yu
National ChiNan University
Department of Information Management
Edit Date: 01/10/2000
Last Update Date: 01/10/2000
ToolKit: JDK1.1
*/
import java.sql.*;
import java.util.*;
import java.io.*;
public class Schema implements Serializable {
Vector tables=null;
String catalogSeparator=null, catalog, schema;
Schema (Connection con, String catalog, String schema) {
this.catalog = catalog;
this.schema = schema;
tables = new Vector();
ForeignKey fk;
try {
ResultSet rs;
DatabaseMetaData md = con.getMetaData();
catalogSeparator = md.getCatalogSeparator();
String[] types = new String;
types = "TABLE";
// get all user defined tables
rs = md.getTables(catalog,schema,null,types);
while (rs.next()) {
Table table = new Table();
tables.addElement(table);
table.catalogName = rs.getString(1);
table.schemaName = rs.getString(2);
table.tableName = rs.getString(3);
table.totalName = getTotalName(table.catalogName,table.schemaName,table.tableName);
table.tableType = rs.getString(4);
table.remarks = rs.getString(5);
}
rs.close();
// get all columns
for (int i=0; i < tables.size(); i++) {
Table check = (Table)tables.elementAt(i);
rs = md.getColumns(check.catalogName, check.schemaName,check.tableName,null);
while (rs.next()) {
Column col = new Column();
col.tableName = check.totalName;
col.columnName = rs.getString(4).trim();
col.dataType = rs.getInt(5);
col.typeName = rs.getString(6).trim();
col.columnSize = rs.getInt(7);
col.decimalDigits = rs.getInt(9);
col.radix = rs.getInt(10);
col.remarks = SQL.fromSQL(rs.getString(12));
col.columnDefault = SQL.fromSQL(rs.getString(13)).trim();
while (col.columnDefault.startsWith("'") || col.columnDefault.startsWith("(")) {
col.columnDefault = col.columnDefault.substring(1,col.columnDefault.length());
}
while (col.columnDefault.endsWith("'") || col.columnDefault.endsWith(")")) {
col.columnDefault = col.columnDefault.substring(0,col.columnDefault.length()-1);
}
col.isNullable = SQL.toString(rs.getBytes(18)).trim();
if (col.remarks==null || col.remarks.equals("")) {
col.remarks=col.columnName;
}
check.addColumn(col);
}
rs.close();
}
// get Primary key
for (int i=0; i < tables.size(); i++) {
Table check = (Table)tables.elementAt(i);
rs = md.getPrimaryKeys(check.catalogName, check.schemaName,check.tableName);
while (rs.next()) {
check.primaryKey.addElement(findColumn(check,rs.getString(4)));
}
rs.close();
}
// get Foreign Keys
for (int i=0; i < tables.size(); i++) {
Table check = (Table)tables.elementAt(i);
rs = md.getImportedKeys(check.catalogName, check.schemaName,check.tableName);
fk = null;
while (rs.next()) {
String tmp1 = rs.getString(1); // remote primary catalog
String tmp2 = rs.getString(2); // remote primary schema
String tmp3 = rs.getString(3); // remote primary table
String tmp4 = rs.getString(4); // remote primary column
String tmp8 = rs.getString(8); // local foreign column
int tmp9 = rs.getInt(9);
if (tmp9 == 1) {
if (fk != null) {
check.addForeignKey(fk);
}
fk = new ForeignKey();
}
fk.primaryTable = findTable(tmp1,tmp2,tmp3);
fk.foreignTable = check;
fk.primary.addElement(findColumn(tmp1,tmp2,tmp3,tmp4));
fk.foreign.addElement(findColumn(check,tmp8));
}
rs.close();
if (fk != null) {
check.addForeignKey(fk);
}
}
// get Reference By
for (int i=0; i < tables.size(); i++) {
Table check = (Table)tables.elementAt(i);
rs = md.getExportedKeys(check.catalogName, check.schemaName,check.tableName);
fk = null;
while (rs.next()) {
String tmp4 = rs.getString(4); // local primary column
String tmp5 = rs.getString(5); // remote foreign catalog
String tmp6 = rs.getString(6); // remote foreign schema
String tmp7 = rs.getString(7); // remote foreign table
String tmp8 = rs.getString(8); // remote foreign column
int tmp9 = rs.getInt(9);
if (tmp9 == 1) {
if (fk != null) {
check.addReferenceBy(fk);
}
fk = new ForeignKey();
}
fk.primaryTable = check;
fk.foreignTable = findTable(tmp5,tmp6,tmp7);
fk.primary.addElement(findColumn(check,tmp4));
fk.foreign.addElement(findColumn(tmp5,tmp6,tmp7,tmp8));
}
rs.close();
if (fk != null) {
check.addReferenceBy(fk);
}
}
} catch (SQLException ex) {
ShowSQLException.show(ex);
} finally {
try {
con.commit();
} catch (Exception e2) {
}
}
}
public Table findTable(String catalog, String schema, String table) {
return findTable(getTotalName(catalog, schema, table));
}
public Table findTable(String totalName) {
int i, j;
for (i=j=0; totalName.indexOf(catalogSeparator,i) != -1; j++) {
i = totalName.indexOf(catalogSeparator,i) + catalogSeparator.length();
}
// How many full name still need to fill? eg student.name ==> ncnu.dbo.student.name
if (j==0) { // we miss all
totalName = catalog+catalogSeparator+schema+catalogSeparator+totalName;
} else if (j==1) { // we miss catalogName
totalName = catalog+catalogSeparator+totalName;
} else { // we have all
}
for (i=0; i < tables.size(); i++) {
if (((Table)tables.elementAt(i)).totalName.equals(totalName)) {
return (Table)tables.elementAt(i);
}
}
return null;
}
public Column findColumn(String totalName, String columnName) {
Table t = findTable(totalName);
if (t == null) {
return null;
}
return findColumn(t, columnName);
}
public Column findColumn(String catalog, String schema, String table, String column) {
Table t = findTable(catalog, schema, table);
if (t == null) {
return null;
}
return findColumn(t, column);
}
public Column findColumn(Table t, String column) {
for (int i=0; i < t.columns.size(); i++) {
if (((Column)t.columns.elementAt(i)).columnName.equals(column)) {
return (Column)t.columns.elementAt(i);
}
}
return null;
}
public String getTotalName(String catalog, String schema, String table) {
String totalName = "";
if (catalog!=null && catalog.trim().length()>0) {
totalName = catalog.trim()+catalogSeparator;
}
if (schema!=null && schema.trim().length()>0) {
totalName += schema.trim()+catalogSeparator;
}
if (table!=null && table.trim().length()>0) {
totalName += table.trim();
}
return totalName;
}
public String getCatalogSeparator() {
return catalogSeparator;
}
public Vector getTables() {
return tables;
}
}
Table.java如下
package ncnu.sql;
/* Program Name: Table.java
Subject: 定義資料表格的屬性
CopyRight: 俞旭昇 Shiuh-Sheng Yu
National Chi-Nan University
Institute of Management Information
Edit Date: 01/03/1998
Last Update Date: 01/04/1997
ToolKit: JDK1.1.5
*/
import java.util.*;
import java.io.Serializable;
public class Table implements Serializable {
String catalogName;
String schemaName;
String tableName;
String totalName;
String tableType;
String remarks;
Vector columns;
Vector primaryKey;
Vector foreignKeys;
Vector referenceBy;
Table() {
columns = new Vector();
foreignKeys = new Vector();
primaryKey = new Vector();
referenceBy = new Vector();
}
void addColumn(Column c) {
columns.addElement(c);
}
Column getColumn(String cname) {
for (int i=0; i < columns.size(); i++) {
Column c = (Column)columns.elementAt(i);
if (c.columnName.equalsIgnoreCase(cname)) {
return c;
}
}
return null;
}
void addForeignKey(ForeignKey fk) {
foreignKeys.addElement(fk);
}
void removeForeignKey(Table t) {
for (int i=0; i < foreignKeys.size(); i++) {
ForeignKey fk = (ForeignKey)foreignKeys.elementAt(i);
if (fk.primaryTable==t) {
foreignKeys.removeElementAt(i);
i--;
}
}
}
void addReferenceBy(ForeignKey fk) {
referenceBy.addElement(fk);
}
void print() {
System.out.println("Table: "+catalogName+"."+schemaName+"."+tableName);
for (int i=0; i < columns.size(); i++) {
((Column)columns.elementAt(i)).print();
}
if (primaryKey != null) {
System.out.println("PrimaryKey:");
for (int i=0; i < primaryKey.size(); i++) {
((Column)primaryKey.elementAt(i)).print();
}
}
if (foreignKeys != null) {
for (int i=0; i < foreignKeys.size(); i++) {
System.out.println("ForeignKey:");
((ForeignKey)foreignKeys.elementAt(i)).print();
}
}
if (referenceBy != null) {
for (int i=0; i < referenceBy.size(); i++) {
System.out.println("Reference By:");
((ForeignKey)referenceBy.elementAt(i)).print();
}
}
}
}
ForeignKey.java如下
package ncnu.sql;
/* Program Name: ForeignKey.java
Subject: Foreign Key, used bye View.java
CopyRight: 俞旭昇 Shiuh-Sheng Yu
National ChiNan University
Department of Information Management
Edit Date: 01/03/1998
Last Update Date: 08/21/1998
ToolKit: JDK1.1.6
*/
import java.util.Vector;
import java.io.Serializable;
public class ForeignKey implements Serializable {
Table primaryTable;
Table foreignTable;
Vector primary; // vector of Columns
Vector foreign; // vecotr of Columns
ForeignKey() {
primary = new Vector();
foreign = new Vector();
}
String getJoinCondition(String sep) {
String cond = "";
for (int i=0; i < primary.size(); i++) {
Column x = (Column)primary.elementAt(i);
Column y = (Column)foreign.elementAt(i);
cond += x.tableName+sep+x.columnName+"="+y.tableName+sep+y.columnName+" and ";
}
return cond;
}
void print() {
System.out.println("ForeignKey:");
for (int i=0; i<primary.size(); i++) {
((Column)primary.elementAt(i)).print();
}
System.out.println("references");
for (int i=0; i<foreign.size(); i++) {
((Column)foreign.elementAt(i)).print();
}
}
}
Column.java如下
package ncnu.sql;
/* Program Name: Column.java
Subject: 定義資料欄位的屬性
CopyRight: 俞旭昇 Shiuh-Sheng Yu
National Chi-Nan University
Institute of Management Information
Edit Date: 01/03/1998
Last Update Date: 01/04/1997
ToolKit: JDK1.1.5
*/
import java.io.Serializable;
import java.sql.Types;
public class Column implements Serializable {
String tableName;
String columnName;
String typeName;
int dataType;
int columnSize;
int decimalDigits;
int radix;
String isNullable;
String remarks;
String columnDefault;
public static boolean isNumeric(int type) {
switch (type) {
case Types.BIGINT:
case Types.TINYINT:
case Types.SMALLINT:
case Types.NUMERIC:
case Types.DECIMAL:
case Types.FLOAT:
case Types.INTEGER:
case Types.REAL:
case Types.DOUBLE:
case Types.BIT:
return true;
}
return false;
}
void print() {
System.out.print(tableName+"."+columnName+" "+typeName+" "+columnSize+" ");
if (typeName.equals("numeric")) {
System.out.print("decimal:"+decimalDigits+" radix:"+radix+" ");
}
System.out.println(isNullable+" "+remarks+" default:"+columnDefault);
}
}
来自：http://programming.im.ncnu.edu.tw/J_index.html
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