SpringJDBC源码解析

傷城~ 2024-04-18 20:39 61阅读 0赞

> 注意，读完本篇文章需要很长很长时间

#### 传统JDBC ####

相信大家对传统的jdbc已经很熟悉了，无非就是下面这个流程

#### 使用SpringJDBC ####

引入maven依赖

实体类

<table> 
 <tbody> 
 <tr> 
 <td><pre>1 2 3 4 5 6 </pre></td> 
 <td><pre>public class User { private int id; private String name; private int age; //getter、setter省略 } </pre></td> 
 </tr> 
 </tbody> 
</table>

返回值处理类

业务处理类

配置类

启动类

至此Deno工程搭建完毕，有需要源码的同学可以从下方地址获取  
https://github.com/shiyujun/spring-framework

#### update ####

我们首先来分析一下update方法的实现

###### 参数封装 ######

<table> 
 <tbody> 
 <tr> 
 <td><pre>1 2 3 4 5 6 7 </pre></td> 
 <td><pre>public int update(String sql, @Nullable Object... args) throws DataAccessException {
 		return update(sql, newArgPreparedStatementSetter(args)); 	} public int update(String sql, @Nullable PreparedStatementSetter pss) throws DataAccessException {
 		return update(new SimplePreparedStatementCreator(sql), pss); 	} </pre></td> 
 </tr> 
 </tbody> 
</table>

可以看到，首先使用了ArgPreparedStatementSetter对参数进行了一层封装，然后又使用了SimplePreparedStatementCreator对SQL进行了封装

###### 核心逻辑 ######

上方这个方法是update的核心逻辑了，这里面的代码不是太多，主要涉及几个核心的逻辑

###### 获取更新条数`updateCount` ######

进入方法以后可以看到这个方法是对`execute`方法的integer返回值的一个封装，也就是此次修改的行数

<table> 
 <tbody> 
 <tr> 
 <td><pre>1 2 3 4 </pre></td> 
 <td><pre>private static int updateCount(@Nullable Integer result) {&nbsp; Assert.state(result != null, "No update count"); return result; } </pre></td> 
 </tr> 
 </tbody> 
</table>

###### 前置方法`execute` ######

这里完成了传统JDBC的前两步加载驱动和获取连接，

###### 执行更新 ######

现在就进入了最后的逻辑了

###### 请求参数设置 ######

<table> 
 <tbody> 
 <tr> 
 <td><pre>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 </pre></td> 
 <td><pre>public void setValues(PreparedStatement ps) throws SQLException {
 		int parameterPosition = 1; 		if (this.args != null &amp;&amp; this.argTypes != null) {
 //遍历参数 			for (int i = 0; i &lt; this.args.length; i++) {
 				Object arg = this.args[i]; //如果是集合的话则递归处理 				if (arg instanceof Collection &amp;&amp; this.argTypes[i] != Types.ARRAY) {
 					Collection&lt;?&gt; entries = (Collection&lt;?&gt;) arg; 					for (Object entry : entries) {
 						if (entry instanceof Object[]) {
 							Object[] valueArray = ((Object[]) entry); 							for (Object argValue : valueArray) {
 								doSetValue(ps, parameterPosition, this.argTypes[i], argValue); 								parameterPosition++; 							} 						} 						else {
 							doSetValue(ps, parameterPosition, this.argTypes[i], entry); 							parameterPosition++; 						} 					} 				} 				else {
 //核心方法 					doSetValue(ps, parameterPosition, this.argTypes[i], arg); 					parameterPosition++; 				} 			} 		} 	} protected void doSetValue(PreparedStatement ps, int parameterPosition, int argType, Object argValue) 			throws SQLException {
 		StatementCreatorUtils.setParameterValue(ps, parameterPosition, argType, argValue); 	} 	 public static void setParameterValue(PreparedStatement ps, int paramIndex, int sqlType, 			@Nullable Object inValue) throws SQLException {
 		setParameterValueInternal(ps, paramIndex, sqlType, null, null, inValue); 	} private static void setParameterValueInternal(PreparedStatement ps, int paramIndex, int sqlType, 			@Nullable String typeName, @Nullable Integer scale, @Nullable Object inValue) throws SQLException {
 		String typeNameToUse = typeName; 		int sqlTypeToUse = sqlType; 		Object inValueToUse = inValue; 		// override type info? 		if (inValue instanceof SqlParameterValue) {
 			SqlParameterValue parameterValue = (SqlParameterValue) inValue; 			if (logger.isDebugEnabled()) {
 				logger.debug("Overriding type info with runtime info from SqlParameterValue: column index " + paramIndex + 						", SQL type " + parameterValue.getSqlType() + ", type name " + parameterValue.getTypeName()); 			} 			if (parameterValue.getSqlType() != SqlTypeValue.TYPE_UNKNOWN) {
 				sqlTypeToUse = parameterValue.getSqlType(); 			} 			if (parameterValue.getTypeName() != null) {
 				typeNameToUse = parameterValue.getTypeName(); 			} 			inValueToUse = parameterValue.getValue(); 		} 		if (logger.isTraceEnabled()) {
 			logger.trace("Setting SQL statement parameter value: column index " + paramIndex + 					", parameter value [" + inValueToUse + 					"], value class [" + (inValueToUse != null ? inValueToUse.getClass().getName() : "null") + 					"], SQL type " + (sqlTypeToUse == SqlTypeValue.TYPE_UNKNOWN ? "unknown" : Integer.toString(sqlTypeToUse))); 		} 		if (inValueToUse == null) {
 			setNull(ps, paramIndex, sqlTypeToUse, typeNameToUse); 		} 		else {
 			//往下看 			setValue(ps, paramIndex, sqlTypeToUse, typeNameToUse, scale, inValueToUse); 		} 	} 	 private static void setValue(PreparedStatement ps, int paramIndex, int sqlType, 			@Nullable String typeName, @Nullable Integer scale, Object inValue) throws SQLException {
 		if (inValue instanceof SqlTypeValue) {
 			((SqlTypeValue) inValue).setTypeValue(ps, paramIndex, sqlType, typeName); 		} 		else if (inValue instanceof SqlValue) {
 			((SqlValue) inValue).setValue(ps, paramIndex); 		} 		else if (sqlType == Types.VARCHAR || sqlType == Types.NVARCHAR || 				sqlType == Types.LONGVARCHAR || sqlType == Types.LONGNVARCHAR) {
 			ps.setString(paramIndex, inValue.toString()); 		} 		else if ((sqlType == Types.CLOB || sqlType == Types.NCLOB) &amp;&amp; isStringValue(inValue.getClass())) {
 			String strVal = inValue.toString(); 			if (strVal.length() &gt; 4000) {
 				// Necessary for older Oracle drivers, in particular when running against an Oracle 10 database. 				// Should also work fine against other drivers/databases since it uses standard JDBC 4.0 API. 				if (sqlType == Types.NCLOB) {
 					ps.setNClob(paramIndex, new StringReader(strVal), strVal.length()); 				} 				else {
 					ps.setClob(paramIndex, new StringReader(strVal), strVal.length()); 				} 				return; 			} 			// Fallback: regular setString binding 			ps.setString(paramIndex, strVal); 		} 		else if (sqlType == Types.DECIMAL || sqlType == Types.NUMERIC) {
 			if (inValue instanceof BigDecimal) {
 				ps.setBigDecimal(paramIndex, (BigDecimal) inValue); 			} 			else if (scale != null) {
 				ps.setObject(paramIndex, inValue, sqlType, scale); 			} 			else {
 				ps.setObject(paramIndex, inValue, sqlType); 			} 		} 		else if (sqlType == Types.BOOLEAN) {
 			if (inValue instanceof Boolean) {
 				ps.setBoolean(paramIndex, (Boolean) inValue); 			} 			else {
 				ps.setObject(paramIndex, inValue, Types.BOOLEAN); 			} 		} 		else if (sqlType == Types.DATE) {
 			if (inValue instanceof java.util.Date) {
 				if (inValue instanceof java.sql.Date) {
 					ps.setDate(paramIndex, (java.sql.Date) inValue); 				} 				else {
 					ps.setDate(paramIndex, new java.sql.Date(((java.util.Date) inValue).getTime())); 				} 			} 			else if (inValue instanceof Calendar) {
 				Calendar cal = (Calendar) inValue; 				ps.setDate(paramIndex, new java.sql.Date(cal.getTime().getTime()), cal); 			} 			else {
 				ps.setObject(paramIndex, inValue, Types.DATE); 			} 		} 		else if (sqlType == Types.TIME) {
 			if (inValue instanceof java.util.Date) {
 				if (inValue instanceof java.sql.Time) {
 					ps.setTime(paramIndex, (java.sql.Time) inValue); 				} 				else {
 					ps.setTime(paramIndex, new java.sql.Time(((java.util.Date) inValue).getTime())); 				} 			} 			else if (inValue instanceof Calendar) {
 				Calendar cal = (Calendar) inValue; 				ps.setTime(paramIndex, new java.sql.Time(cal.getTime().getTime()), cal); 			} 			else {
 				ps.setObject(paramIndex, inValue, Types.TIME); 			} 		} 		else if (sqlType == Types.TIMESTAMP) {
 			if (inValue instanceof java.util.Date) {
 				if (inValue instanceof java.sql.Timestamp) {
 					ps.setTimestamp(paramIndex, (java.sql.Timestamp) inValue); 				} 				else {
 					ps.setTimestamp(paramIndex, new java.sql.Timestamp(((java.util.Date) inValue).getTime())); 				} 			} 			else if (inValue instanceof Calendar) {
 				Calendar cal = (Calendar) inValue; 				ps.setTimestamp(paramIndex, new java.sql.Timestamp(cal.getTime().getTime()), cal); 			} 			else {
 				ps.setObject(paramIndex, inValue, Types.TIMESTAMP); 			} 		} 		else if (sqlType == SqlTypeValue.TYPE_UNKNOWN || (sqlType == Types.OTHER &amp;&amp; 				"Oracle".equals(ps.getConnection().getMetaData().getDatabaseProductName()))) {
 			if (isStringValue(inValue.getClass())) {
 				ps.setString(paramIndex, inValue.toString()); 			} 			else if (isDateValue(inValue.getClass())) {
 				ps.setTimestamp(paramIndex, new java.sql.Timestamp(((java.util.Date) inValue).getTime())); 			} 			else if (inValue instanceof Calendar) {
 				Calendar cal = (Calendar) inValue; 				ps.setTimestamp(paramIndex, new java.sql.Timestamp(cal.getTime().getTime()), cal); 			} 			else {
 				// Fall back to generic setObject call without SQL type specified. 				ps.setObject(paramIndex, inValue); 			} 		} 		else {
 			// Fall back to generic setObject call with SQL type specified. 			ps.setObject(paramIndex, inValue, sqlType); 		} 	} </pre></td> 
 </tr> 
 </tbody> 
</table>

至此update方法更新分析完毕

#### query ####

<table> 
 <tbody> 
 <tr> 
 <td><pre>1 2 3 4 5 </pre></td> 
 <td><pre>public &lt;T&gt; List&lt;T&gt; query(String sql, @Nullable Object[] args, RowMapper&lt;T&gt; rowMapper) throws DataAccessException {
 return result(query(sql, args, new RowMapperResultSetExtractor&lt;&gt;(rowMapper))); } </pre></td> 
 </tr> 
 </tbody> 
</table>

首先最外层的result方法没有什么特别的，就是对返回值的处理

<table> 
 <tbody> 
 <tr> 
 <td><pre>1 2 3 4 </pre></td> 
 <td><pre>private static &lt;T&gt; T result(@Nullable T result) {
 		Assert.state(result != null, "No result"); 		return result; 	} </pre></td> 
 </tr> 
 </tbody> 
</table>

###### 参数封装 ######

接着同样是封装请求参数

<table> 
 <tbody> 
 <tr> 
 <td><pre>1 2 3 4 5 6 </pre></td> 
 <td><pre>public &lt;T&gt; T query(String sql, @Nullable Object[] args, ResultSetExtractor&lt;T&gt; rse) throws DataAccessException {
 		return query(sql, newArgPreparedStatementSetter(args), rse); 	} public &lt;T&gt; T query(String sql, @Nullable PreparedStatementSetter pss, ResultSetExtractor&lt;T&gt; rse) throws DataAccessException {
 		return query(new SimplePreparedStatementCreator(sql), pss, rse); 	} </pre></td> 
 </tr> 
 </tbody> 
</table>

###### 核心查询 ######

###### 处理返回值 ######

因为修改的时候只需要返回一个int值修改的条数就ok了，但是查询的时候各种查询的类型什么的就不一样了。所以在这需要单独处理一下

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