http断点续传简单实现（java)

/* P,I3E?! j  
**SiteFileFetch.java OK3B6T5w=  
*/ Axj<e!{D  
package NetFox; ^4 es  
import java.io.*; ^C<dr}8  
import java.net.*; _or$^.='  
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public class SiteFileFetch extends Thread { i,;Q  
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SiteInfoBean siteInfoBean = null; //文件信息Bean bsqoR8  
long[] nStartPos; //开始位置 Haq23K  
long[] nEndPos; //结束位置 O}#*U+j  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 Gp32\^H|<  
long nFileLength; //文件长度 RoJ&dK  
boolean bFirst = true; //是否第一次取文件 yU .B(|  
boolean bStop = false; //停止标志 U?xl%qF`)  
File tmpFile; //文件下载的临时信息 tH>%`:  
DataOutputStream output; //输出到文件的输出流 Y*w<~m  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 4fP>;9[F  
public SiteFileFetch(SiteInfoBean bean) throws IOException ]6=cSs!  
{ :*}tkr4&eh  
siteInfoBean = bean; e5veq!*C?  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); &^&k]JBaV  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 60X B  
if(tmpFile.exists ()) x%cKTpDh!  
{ (_<ruwV]`  
bFirst = false; ukG1<j7.  
read_nPos(); zg8m(=k'  
} f"k/j?e*  
else |$bZO`^  
{ joM98H@  
nStartPos = new long[bean.getNSplitter()]; _|*3uGo:  
nEndPos = new long[bean.getNSplitter()]; Jc{zi^)(EN  
} jZm1.{[>  
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} &yVii^  
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public void run() -R6z/P(}  
{ 1*>a  
//获得文件长度 Q#:,s8TW[  
//分割文件 #c?\(qjWA  
//实例FileSplitterFetch +=O8t0y n  
//启动FileSplitterFetch线程 _NqEhf:8  
//等待子线程返回 A:
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try{ Q v{q:=k  
if(bFirst)
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{ >@ge[MuS  
nFileLength = getFileSize(); LX*T<|c`'  
if(nFileLength == -1) +TUtVG  
{ z KJ6j]m  
System.err.println("File Length is not known!"); 6PJ0iten  
} jL`S6E?7  
else if(nFileLength == -2) '1.T-.4>&  
{ <M+ZlF-`  
System.err.println("File is not access!"); O a-ZeCq  
} $:mCyP<y  
else ^dqyX(
 
{ WOgbz&S?J  
for(int i=0;i<nStartPos.length;i++) A"S})  
{ Kr]F+erJe  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); eJJvEvZ,  
} ,gkxZ{Eh  
for(int i=0;i<nEndPos.length-1;i++) Ce`{M&NSWX  
{ ;QgJw2G  
nEndPos = nStartPos[i+1]; 9>%f99n  
} !;iySRZr  
nEndPos[nEndPos.length-1] = nFileLength; ULQ*cW&;?  
} `wk#5[Y_  
} 5QMu=/  
q] ,&$d^@  
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//启动子线程 WERK JA  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; atW;S99#  
for(int i=0;i<nStartPos.length;i++)
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{ v*]|1q%/  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), CQ3;NY=o  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), = #ocp  
nStartPos,nEndPos,i); my*UN_]  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); X3RpJ#m"'  
fileSplitterFetch.start(); 3haY{CEr  
} j:]/AReOL  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), "R):B~8|H{  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); e2/&X;2  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", {-<h5_h@  
nEndPos = " + nFileLength); `iQyKZS/+  
// fileSplitterFetch[nPos.length-1].start(); t{84ioJ"$  
#2x\d  
p~=%CG^5  
//等待子线程结束 BflF*-s ^  
//int count = 0; PO |p53  
//是否结束while循环 Jq?a
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boolean breakWhile = false; ##R]$-<4dQ  
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while(!bStop) 0g`WRe  
{ m,)Re8W-  
write_nPos(); 6OIA>%{  
Utility.sleep(500); p3sz32RX  
breakWhile = true; % J+'7'g  
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for(int i=0;i<nStartPos.length;i++) =EV8~hMyqh  
{ mN~;MR;  
if(!fileSplitterFetch.bDownOver) C7)].vUN  
{ :@YZ6?hf  
breakWhile = false; .@1\26<  
break; 3MkF  
} t
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} kk^KaD4dA  
if(breakWhile) Vf O0 z5&  
break;
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9)mJo(  
//count++; _(oJ8h(  
//if(count>4) u~a<Psp&|  
// siteStop(); ]FsPlxk6  
} 2b3x
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System.err.println("文件下载结束！"); ^\Jg {9a  
} qRB&R$  
catch(Exception e){e.printStackTrace ();} C 5)G^  
} 5b|_?Em7  
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//获得文件长度 ^Z2%b>  
public long getFileSize() [R& P.E7w'  
{ 3}Uae#oy  
int nFileLength = -1; 1xcx2L+R  
try{ =}_c=z?UY  
URL url = new URL(siteInfoBean.getSSiteURL()); *|hICTWL  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); KHdj#3<AR  
httpConnection.setRequestProperty("User-Agent","NetFox"); zBqr15  
#YjV3O5<  
,!u^E|24  
int responseCode=httpConnection.getResponseCode(); NoiU5pP  
if(responseCode>=400) ]3Mm"7`  
{ SE%i@}  
processErrorCode(responseCode); ezHj?@  
return -2; //-2 represent access is error [o>/2  
} D`,@EW].  
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String sHeader; 4}#*M2wb  
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for(int i=1;;i++) X9zTz2 Fy  
{ WE
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ]Jv Z:'g}  
//Utility.log(in.readLine());
}RW4  
sHeader=httpConnection.getHeaderFieldKey(i); )M^;6S  
if(sHeader!=null) y 0M&Bh  
{ qfN<w&P  
if(sHeader.equals("Content-Length")) Z&J417buk  
{ zgVplp  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); d|DIqT~{W  
break; 1gH5#_?  
} zB 7wGl9  
} <1_?.gSi  
else >-+MWu=  
break; dv@6wp:  
} r_ r+&4n  
} uA\A4  
catch(IOException e){e.printStackTrace ();} IcaIB
)  
catch(Exception e){e.printStackTrace ();} OJkPlDym  
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Utility.log(nFileLength); [o|]>(tk  
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return nFileLength; G|Q}.v  
} ux{OgFfi  
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//保存下载信息（文件指针位置） & }k=V4L  
private void write_nPos() "fz-h  
{ nb?bx{M  
try{ 5)&e2V',y  
output = new DataOutputStream(new FileOutputStream(tmpFile)); REFisH-  
output.writeInt(nStartPos.length); Bg7?1m  
for(int i=0;i<nStartPos.length;i++) Uf_w o  
{ gxt2Mq;q~}  
// output.writeLong(nPos); 9x{T"'  
output.writeLong(fileSplitterFetch.nStartPos); {SK8Mdn  
output.writeLong(fileSplitterFetch.nEndPos); ^_2Ki  
} <&W3\/xx  
output.close(); !M3Iu
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} [iL2c=_  
catch(IOException e){e.printStackTrace ();} Y^3tk}yru  
catch(Exception e){e.printStackTrace ();} 7W}~c/%  
} ) e;F@o3  
}yB@?  

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//读取保存的下载信息（文件指针位置） ojyG|Y  
private void read_nPos() T5Pc2
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{ Z< uwqA  
try{ 9f BD.9A  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); e(!a~{(kq%  
int nCount = input.readInt(); wl(}F^:/`  
nStartPos = new long[nCount]; d@#=cvW  
nEndPos = new long[nCount];
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for(int i=0;i<nStartPos.length;i++) EHo"y.ODg  
{ XUMCz7&j  
nStartPos = input.readLong(); : PQA9U|  
nEndPos = input.readLong(); *?\2Ohp  
} /a9+R)Al  
input.close(); <_42h|-  
} ZO0_:T
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catch(IOException e){e.printStackTrace ();} ;{HxY98Q  
catch(Exception e){e.printStackTrace ();} +86\&y)
 
} ;5 IS58L  
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private void processErrorCode(int nErrorCode) u&pLF%'EQ  
{ KZD&Ih(vC  
System.err.println("Error Code : " + nErrorCode); @^;\(If2  
} 9rA3qj%  
1X#`NUJ?2  
^!kvgm<{$  
//停止文件下载 $g1p!  
public void siteStop() y/kCzDT,  
{
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bStop = true; nNQ\rO  
for(int i=0;i<nStartPos.length;i++) %e1<N8E4  
fileSplitterFetch.splitterStop(); R@"N{ [9  
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} EaP#~x  
} QP\vN|r  
//负责部分文件的抓取 `_<AZ{&&  
**FileSplitterFetch.java lXB_HDY  
*/ MTLcLmdO  
package NetFox; YW/<. 0rI  
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import java.io.*; ^//N-?Fx  
import java.net.*; =Oo*7|Z  
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public class FileSplitterFetch extends Thread { VfZ/SByh7p  
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String sURL; //File URL '{7A1yJnY%  
long nStartPos; //File Snippet Start Position ]%mg(&p4  
long nEndPos; //File Snippet End Position {/ty{  
int nThreadID; //Thread's ID 5_`.9@eh.  
boolean bDownOver = false; //Downing is over x80~j(uVf  
boolean bStop = false; //Stop identical F92n)*[  
FileAccessI fileAccessI = null; //File Access interface M5%xp.B  
*b7v)d#  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException *$hO C%(  
{ 6\E |`  
this.sURL = sURL; *nH?o* #  
this.nStartPos = nStart; Ebq5P$  
this.nEndPos = nEnd; g[eI-J+F
 
nThreadID = id; tcRK\  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 3mBrnq]j>  
} f'#7i@Je  
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public void run() !\"C
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{ %K%8 ~B  
while(nStartPos < nEndPos && !bStop) D|+H!f{k  
{ *Qyw _Q  
}Y-f+qX*  
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try{ @c{Z?>dUc#  
URL url = new URL(sURL); +$v$P!),  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); k_y@vW3  
httpConnection.setRequestProperty("User-Agent","NetFox"); Q2Q`g`*O:  
String sProperty = "bytes="+nStartPos+"-"; 
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httpConnection.setRequestProperty("RANGE",sProperty); qed; UyN  
Utility.log(sProperty); ;w@:  
@B1rtw6  
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InputStream input = httpConnection.getInputStream(); ff{ESFtD  
//logResponseHead(httpConnection); v3hNvcMpf  
+\}]`uS:  
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byte[] b = new byte[1024]; us5`?XeX]  
int nRead; op"Cc  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) <xc"y|7X  
{ |1t30_ /gS  
nStartPos += fileAccessI.write(b,0,nRead); Ozn7C?\*  
//if(nThreadID == 1) x9@%L{*  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); `;i| %$TU  
} |7f}icXKur  
;
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Q
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Utility.log("Thread " + nThreadID + " is over!");  -EITz  
bDownOver = true; <'s1+^LC  
//nPos = fileAccessI.write (b,0,nRead); [#14
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} /'">H-r  
catch(Exception e){e.printStackTrace ();} W'6*$Ron  
} ~_h4
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} xat)9Yb}0  
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//打印回应的头信息 BT`6v+,h7k  
public void logResponseHead(HttpURLConnection con) . vYGJ8(P  
{ "-I>  
for(int i=1;;i++) =0m[  
{ czedn_}%Q  
String header=con.getHeaderFieldKey(i); nY(jN D  
if(header!=null) a{]1H4+bQ  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); T0aK1Lh  
Utility.log(header+" : "+con.getHeaderField(header)); qQVqS7 t  
else @^`f~0#:  
break; d~28!E+  
} WL$WWA08_  
} (VC_vz-  
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public void splitterStop() ( 6r9y3'  
{ BHU(
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bStop = true; ts)0+x  
} %OW[rbE.  
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} f~"3#MaV  
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/* v "oO  
**FileAccess.java #<se0CJB  
*//文件访问(定位，写) }S%a]  
package NetFox; s-k-|4  
import java.io.*; !%5{jO1  
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public class FileAccessI implements Serializable{ 93YD\R+q  
to,=Q8)0  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 BPi>SI0  
RandomAccessFile oSavedFile; nw\p3  
long nPos; m<OxO\Mpf  
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public FileAccessI() throws IOException n>iPAD  
{ LzgD#K
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this("",0); a^s
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} c*\^61T  
f+/^1~^  
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public FileAccessI(String sName,long nPos) throws IOException R HF;AX n  
{ 
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oSavedFile = new RandomAccessFile(sName,"rw"); RRq*CLj  
this.nPos = nPos; 0.+iVOz+Y  
oSavedFile.seek(nPos); Ke,-8e#Q  
} XFBk:~}sI  
8V4Qyi|@F  
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public synchronized int write(byte[] b,int nStart,int nLen) |y=CmNG,  
{
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int n = -1; q F}5mUcZ4  
try{ EBebyQcon  
oSavedFile.write(b,nStart,nLen); e HOm^.gd  
n = nLen; ClfpA?vv  
} 6^ KDc  
catch(IOException e) SX FF  
{ Ye )(9  
e.printStackTrace (); I5 2wTl0  
} t+?\4+!<  
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return n; {= z%('^  
} WMI/Y9N  
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} E!Ng=}G&_  
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}D=h"\_=  
/* +ckj]yA;  
**SiteInfoBean.java tv;3~Y0i  
*/ }  g  
package NetFox; 7IIM8/BI  
(+Uo;)~!YC  
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public class SiteInfoBean { 6=H-H\iw  
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+bQn2PG=  
private String sSiteURL; //Site's URL | _S9U|  
private String sFilePath; //Saved File's Path ,p 'M@[  
private String sFileName; //Saved File's Name O&X-)g=  
private int nSplitter; //Count of Splited Downloading File ;eA~z"g  
{+`ep\.$&  
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public SiteInfoBean() Sa<R8X'J  
{//nSplitter的缺省值为5 i:zA(  
//default value of nSplitter is 5 s%/0WW0y^  
this("","","",5); 8zY)0  
} ( Ni
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}Rf } iG  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) _wqFKj  
{ 1yKf=LZ^  
sSiteURL= sURL; WK<pZ *x  
sFilePath = sPath; uZ'5&k96T  
sFileName = sName; ll5Kd=3  
this.nSplitter = nSpiltter; "n05y}  
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} N4D_ 43jz  
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public String getSSiteURL() ,$G89jSM  
{ 0 Q1}u@G  
return sSiteURL; m.4y=69 &  
} f.8L<<5 c  
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;aFQP:l/  
public void setSSiteURL(String value) ?c43cYb  
{ *]H ./a:1  
sSiteURL = value; ksK lw_%o  
} 4b<:67 %  
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oZzE.Q1T  
public String getSFilePath() k,&W5zBKe  
{ &2Y>yFB ,  
return sFilePath; zPVA6~|l  
} GEvif4  
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public void setSFilePath(String value) g:*yjj  
{ Y${ $7+@  
sFilePath = value;  M,6AD]  
}  k/t4  
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fY6&PuDf.  
public String getSFileName() ",K6zALJ  
{ *D9QwQ _|  
return sFileName; H-S28%.  
} t;? q#!uc  
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public void setSFileName(String value) a(<nk5  
{ ;=E3f^'s  
sFileName = value; d:j$!@o  
} hio{
: (  
Oc"2|X  
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public int getNSplitter() C f<,\Aav  
{ ^h' wZ7-\  
return nSplitter; 3<'n>'  
} \?}ZXKuJj  
)v'DQAL  
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public void setNSplitter(int nCount) [g%oo3`A  
{ T}zOM%]]  
nSplitter = nCount; 9BF#R<}h  
} .m4K ]^m  
} 0Uybh.dC  
udw5A*Ls  
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/* 9oN b= .  
**Utility.java +p_SKk!%+  
*/ 4sG^bZ,  
package NetFox; `s.y!(`q  
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z*
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public class Utility { xKIm2% U9  
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public Utility() fRq2sK;+  
{ <<[`;"CF  
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} Vw+U?  
sg2T)^*V  
//线程睡眠 y%z$_V]  
public static void sleep(int nSecond) )5p0fw  
{ XN??^1{J}]  
try{ <w8*Ly:L  
Thread.sleep(nSecond); m~%IHWO'  
} z$S)|6Q  
catch(Exception e) F~&bg
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{ BQ &|=a6  
e.printStackTrace (); #_|6yo}  
} PT|t6V"wd  
} =Cu!  
qm]k (/w  
//日志 >f74]J=V  
public static void log(String sMsg) YY'46  
{ "1WwSh}Z  
System.err.println(sMsg); 1Hk`i%  
} x2(
hp  
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5Z1b9.;.,  
public static void log(int sMsg) R$_#7>3  
{ %^kBcId  
System.err.println(sMsg); 6|~N5E~SX  
} Z!v)zH\  
} #]cO] I  
L>Y%$|4  
Xu2:yf4No*  
/* [,yoFm%"  
**TestMethod.java :$L^l{gT  
*/ /X9Kg  
package NetFox; A )tGB&  
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.T#h5[S2x  
public class TestMethod { STtjkZ6  
1-.6psE  
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public TestMethod() W;P8=q  
{ ///xx/weblogic60b2_win.exe 6Q"fRXM  
try{ Hyh$-iCa  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); l`>|XUf6  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); a9}7K/Y=d  
SiteFileFetch fileFetch = new SiteFileFetch(bean); @FO=0_;y  
fileFetch.start(); 0go{gUI  
} /m"O.17N  
catch(Exception e){e.printStackTrace ();} 1P;J%.{  
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# 3UrGom  
} bys5IOP{]o  
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public static void main(String[] args) |zd+ \o  
{ gc,%A'OR^<  
new TestMethod(); n-P<y  
} icS%])3LF  
}
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